groze: Unless those sane people are misled into the mansion by their double-crossing boss, and especially when the mansion looks like a good alternative to staying in the woods packed with zombified dogs. ;P
langurmonkey: I'd take my chances with the zombie dogs. If they get to be too much for me, I can always climb up a tree. Monkey style.
Seriously, did you play the game in question? A Special Forces Police team is sent to the mountains in search of the team they'd sent there previously to investigate some bizarre murders, who disappeared. The chopper that took them there takes off to fuel up and they are abandoned there. Soon they find the remnants of the first team in a destroyed helicopter, and then a huge pack of zombie dogs attacks them out of nowhere, killing one of the team members instantly. The rest of the team are frightened because they have no clue of what those things are, but they are trained military so they try fighting them off, to no avail whatsoever. Wesker, the team leader, suddenly saves Chris from being mauled by a zombie dog and urges the survivors to hide in the mansion, a command they more than willingly obey, given the confusion they were suddenly thrown into.
So, what's not realistic about this, if not for the fact there are no zombies in the "real world"? As far as human behavior goes, I see nothing wrong.
(And yay for derailing threads!)