Awkward situation- not pregnancy related

So my cousin who I've spoke to maybe once in my life messaged me tonight. He wants to move to my city (I have no family here) and stay on my couch as he put it until he finds a place. He lives far away and is a college drop out, can't hold a job, and is info alcholol and hard drugs. Obviously he's not staying here...my other cousin that I'm close to used to be his best friend and they don't speak due to my good cousin lending him money etc. Anyway he asked me on Facebook if he could stay on my couch while he finds a place. First off, he's about 12 years older than me, he doesn't drive, doesn't have a car, doesn't have a degree. Secondly I have a baby and a two year old. We don't have space even if I wanted to. I'm certinaly not exposing my kids to that. I have an education, a good job, my husband has a good job and we own our vehicles and house. My question is do I just ignore hjm on Facebook or should I say no?? I literally barely know him...so I don't really mind just ignoring him. I don't know