Rescue ~Hope I'm doing the right thing~

I was in petco today, and someone had dropped off a rat that they could no longer take care of, and he's up for adoption. He's full grown, definatly older, lumpy, and has some old wounds on him, but hes sweet as pie and I can't stand the thought of him going to a bad home, being put down, or going in the stomach of someone python or boa. So I've decided that if hes still there tomorrow that hes coming home with me. I've already thought of a name for him, Kato which is African for "second chance" He's going to live alone, I don't want to chance putting him with my young healthy males, but I just can't turn him down. I hope I'm doing the right thing.