A coach is not going to say "make sure he has alcohol available." But I don't think coaches are stupid. I'm sure they are aware that if the player is staying for an overnight, there will be some form of socializing going on. And regardless of how strict the program's rules are, as I said, consuming alcohol is extremely easy at college.
My college coach has expressed that he doesn't like having overnights unless the player lives more than 4 hours away. If a player and his family are capable of making a day trip out of a recruiting trip then that's what he would prefer. If a player that he is recruiting requests an overnight and lives fairly close to the school then he tends to think that the player is more interested in experiencing the social aspect of the school than just focusing on the athletic and academic portions that can be seen in a day.