That's a good question, well if its before Billie comes out as an angel, then it would be over something other than the fact she is selling Billies blood. I kind of picture Logan getting cut off before she comes out, because he wouldn't have a reason to be thirsty. Though the cut off wouldn't be permenant until after. 

Also Molly will be pissed, and she runs the main supply trade of the school so she is going to make it known anyone that gives Logan blood is cut off. But you're right they still have their friends. And Billies supply but he might feel bad for using that.

The fact Molly is avoiding would quickly be noticed too because she would switch her first class, first thing in the morning she would go to Kane or Arch Mage to switch it. Haha it possibly would end up coming to that.

Haha.