I assume someone brought this up, but when Izuru was talking to Nagito on the boat, did he make any statements that absolutely noted that he was bringing the Monokuma virus to the NWP? Could it be that instead, he brings AI Chiaki? Given the fact that he obviously feels pained about Chiaki's death, it would stand to reason that he would want to save her classmates - and who better to do that than Chiaki?
To be fair, no one except Nagito noticed that Impostor was acting strangely, and since he was injured whenever he saw Mikan, he may not have been able to think about that.
It was a little extreme, but Juzo being gay and self-loathing is an all-too-common problem. It's especially the case in Japan, where being openly gay is shameful af, especially for someone like him who is a national icon.