He consciously chose to stop trying to avoid squishing bugs, I think that's when he activated his mana body attack, like he used against the ghosts before. He's swatting away the shadows and stepping on the bugs more firmly, deliberately. I don't think he has that kind of "hostile intent" when he bumps into people.
Edit: Plus, it looks like the fodder bugs were scared off when he decided to squish anything that gets in his way, they clear a space around him, leaving only that boss bug.
Fuck you're right, somehow I forgot that detail while writing
It makes sense cause if they could unconsciously use their power the people around them would be fucked :V
I imagine whatever system is behind the dungeons leaves only passive stuff always enabled, like for example having high defense making you more resistant to attack so it's harder for you to get hurt even out of dungeon
System being like that also explain why he doesn't realize he's so powerful as there's no way for him to accidentally use whatever powers he got, after all as far as he knows he's only killing pests so he won't accidentally blow a mountain or whatever and realize he's way stronger cause he's not trying to use so much power
It also explains why government help fool him he's a regular human is a viable at all, if he can't accidentally use too much power they're able to keep the charade by just bullshiting him all the way, as long as he doesn't willfully try to use more power he just won't realize he's way beyond normal humans
I kinda like how the system is pretty subtle instead of going usual status screen slop, makes me wonder if we'll get mores details on it since so far the only thing we got is from Kuro evolving
And you're right about the bugs too which kinda makes me wonder why mob bugs ran away while the boss still tried attacking, maybe because he didn't see the boss so there was no hostile intent against it? After all he didn't even notice it