I read a story on the internet when I went researching, nothing to do with premies it was written by a Japanese man.  When he was little his mother used to take him with her to meet her friend at the park.  The two women would chat about their husbands and how horrible they were.  I'm assuming they did the sexual action with their little sons to keep them quiet while they talked but the angrier she got talking about her husband, the harder she would pull on his penis - not exactly affectionate touching that, is it.  He said it was painful.

so, and this is the point here - you're not their son, you weren't even witness to it were you?  Not your place to say if it were 'affectionate touching' or not.

Oh, and just want to add I do Not believe it is ever okay to do that to your babies.  How many times do we have to say it isn't good?