[AkibaSilver]

I think the way I read it is that Tachibana finally realised that, with his last bit of normal human-mind that BOARD didn't beat out of him during basic training, maybe dousing himself in seaweed drugs is messing with his mind, and that might not be a good thing, especially when the only person who he might have let close is willing to go full domestic bliss just to convince him to change. As much as Tachibana is a selfish semi-coward who wants to be strong, there's still some part of him that cares for other people, and while he might have made some mistakes that make him scared to listen, his moral core is in there somwhere.

Of course, being Tachibana, he does it at the worst possible time, but hey, he's trying!