My 19 year old twin sister wants to date a 30 year old who lives in fraternity with criminal record, not ok?

My sister and i are really close and usually agree on everything, but this is where we seem to be at a disconnect. How does someone think it is ok to date a man 11 years older that not only lives in a fraternity with college kids, but also has been in prison and caught with drugs multiple times. Does this situation sound ok to anyone other than my sister?