I mean from our POV it wasn't justified at all because we know that Santana was right... But Kurt and Rachel don't know that and Santana did invade their privacy and showed up out of the blue uninvited (yes I went there).

So it was partly justified.

^exactly they didn't invite her she just showed up. she did go through all of there stuff, plus her just showing up at there school could cause problems for them and brody was there first and they didn't know that she was just trying to help

I totally understand where they were coming from and tbh if I had a roommate acting like she was I would probably do the same. But it was still a little insensitive for them to not make an attempt to consider her point of view or pause before kicking a friend who they grew up with out.