Well...the residents of Tenpenny Tower do seem to be a bit luxurious, not researching into things, such as feral/non-feral ghouls. I guess it's fair to say that the residents, aren't quite sure of the harm, that the ghouls might or might not inflict, to them. The reason that you would probably receive bad karma is cause it's sorta like an act of being close-minded and not opening your tolerance to a different "race". It's like being racist. And in the game...the residents of Tenpenny Tower are viewed as racists or "skinnist" towards ghouls, which is mean and bad.
So siding with them, can be a bad thing. However, if you like ghouls and want to get them into the Tower, WITHOUT having them kill any of the residents, just ask Tenpenny, once you meet up with Roy in the sewers. Tenpenny will give you a list of people to convince, so that ghouls can come stay in the tower. You can either convince those certain people, to be okay with ghouls, entering their homes or threaten them(With a speech check) that ghouls will move in and tell them to pack their things.
Once you got all approvals from all of the people on the list, head back to Tenpenny and inform him. He will tell you that it is okay, for ghouls to stay there. Then you just walk back to Roy Phillips and tell him the good news. He walks to the Tower and then him and his ghoul friends, appear there.
If you go upstairs to Tenpenny's room, you will see blood swiped across the edge of the bathtub.
Talking with Roy, he tells you that him and Tenpenny "met up" for a long-awaited meeting.
With this...you can have ghouls stay at the Tower, along with having Tenpenny dead and gone(Note: You might not wanna do this, if you haven't finished the "You Gotta Shoot 'Em In The Head" quest, as Tenpenny is involved in this).