I had similar problem. You can try entering the building in stealth mode, that way all NPCs don't turn hostile. It worked for me, although I'm not sure which behavior is a bug, NPCs turning hostile when you reenter or them acting normal when you reenter in stealth mode.
Might is not "strength" like in all other games with stats.
And yet, when you look at how it's being used as a skill check in dialogs, it most definitely looks like strength