No, despite how some (viewers and others characters in the show, sometimes as part of Tendou's plan) interpret what he's said, Tendou never believed in killing all Worms, just the ones who threatened humanity (the vast majority of them). The Worm that Tendou finished in episode 31 who was begging for mercy is one who broke off from the large group of them earlier in the episode. The exchange between Kagami and Tendou after that scene will explain it:
Kagami: "Do you ever hesitate before killing a Worm? The Worm hold the memories of the humans they mimic."
Tendou: "If I hesitate, I will be the one that dies."
Like several dangerous Worms before him, that Worm was obviously trying to appeal to Tendou's compassion by using his mimic form and pleading for mercy. If you let a Worm manipulate your emotions, you'll end up dead. Ryo-Worm would have killed Kagami, Daisuke's favorite customer's mimic would have killed him and though there was some good still left in Makoto-Worm, he and his brethren killed Kagami (who was of course, resurrected as Gatack). Tendou obviously protected Hiyori and other good Natives and he only defeated Tsurugi beacuse that's what Tsurugi wanted. He left Reina up to Daisuke, who was losing her humanity again and needed to be put down, because she was a threat to humanity.
So Tendou obviously did lose it for a few episodes, his paranoia regarding Hiyori's safety leading him to strip the Zecters from the Riders that he couldn't trust) and being especially confrontational, but he never lost his morality.
I'm pretty sure it was a while before Tendou believed that not all Worms were a threat to humanity. I distinctly remember him saying something along those lines somewhere in the early 40s. Also, around when Kagami became Gatack and he said maybe all Worms aren't evil, Tendou called him naive, so I'm fairly certain that for the majority of the series, Tendou believed all Worms to be a threat.Wwhich is why I think he was able to put up a good argument with Negishi when he said that humans were all a threat; he's felt like that before, he knows the thinking and knows how it was flawed.
Hesitation is needed in battle sometimes. You can't always expect things to go your way or to know every possible outcome, if you think like that, you will likely end up doing something too rash. That's not to say that you should let your opponent manipulate the way that you think, but you have to examine how things are going and if someone really does deserve to die. Life is irreplaceable, Kabuto is strong, he could have easily held off that Worm until he knew for sure if it had killed someone else.
Tendou, as a character, ended in a better place than when he started. I just feel that it took too long for him to realize something as obvious as noticing that just because one member of a race does something doesn't mean they're all bad.
It wasn't just that he was unabashedly arrogant, it was that he continuously proved himself and justified his arrogance. He inspired awe through his combat prowess, keen intellect (identifying Worms, managing to infiltrate churches, hospitals, the police, etc.) and exceeding normal human limits. All of the lofty metaphors he uses for himself were appropriate, given his role int he series, in relation to the other characters. He is the sun and no matter how bright the other stars shine, they'll never be a match for the sun.
What I didn't like is that a lot of the times, he set the bar for what was just and if people didn't do things his way, they had to be stopped. Arrogance is one thing, but pushing that on other people is going to far in my opinion. I believe that last line to be a very flawed belief on Tendou's part. There is nothing wrong with believing that you are a strong person and that you are better than a lot of others, but believing that no one will ever exceed you is just ludicrous. There were lots of times when he was beaten in battle, Cassisworm owned him in their first battle, sure Tendou eventually found a way to beat him, but that doesn't negate the fact that he was beaten at one point in time. Tendou is able to adapt and that's a good thing, but he went over the top in his self righteous behaviors sometimes.
It's something that I think he realized by the end of the series. He can't do everything by himself and he does need the help of others at times. Again, I like where he ended up, it's just the way that he got there I did not like.
Hidenori's character Yaguruma was similar to Tendou's at first, so I can see that. I can't imagine Hosokawa portraying Tendou, because it's such a different role from Hibiki, who is a friendly, lighthearted person with a song in his heart. That doesn't mean he isn't capable of playing a character like Tendou, I just have a difficult time picturing it.
Probably should have been more clear on that one, sorry. I meant that Hosokawa could portray Tendou better with the type of Tendou we had in the first four episodes or so. Even though he wouldn't be as strong as in the first four episodes, I think he could do a good job as Tendou later on in the series. He's done some good roles like that in the past. But now that I think of it, Ken'ichi Matsuyama really would have been an ideal Tendou. If you've ever seen Death Note, he plays arrogant characters pretty well and without coming off like a huge ass, which I think was a side effect of Mizushima's inexperience in such roles and one of the main reasons I didn't like Tendou a lot. I like good and arrogant characters, but with the way he was acted, I just couldn't like Tendou that much.