@RamenRider exactly. This made no sense. A normal person wouldn't ever trust or accept being under these guys again, let alone Bat, who doesn't look like the type to take bullshit from others.
Like for real, what if blue or those guys hadn't shown up? 'haha oopsie. i transformed him into a cyborg against his will, my bad tee hee', and then they'd receive a little slap on their wrists.
The only explanations, i think, that would make this plausible were if either Bat is indeed just there to gather some info on the Neo Heroes, or if he got reluctant to fight so many strong people at once at that moment. Even so, that'd go a bit against his character. A third possible explanation would be because he does not want to risk the safety of his sister, but that's about it.