I think it is more of a scare tactic to deter it then it is a threat to actually punish any school. How could you truly enforce it?
Think about it, technically any human being with a twitter account regardless of whether they are even a fan of a school could be deemed a booster under this definition.
Let me give you an example. Some kid, John Smith in Butte, Montana we'll say, tweets to recruit X that he should attend SJU. John Smith never went to SJU, never gave a dime to SJU, has never even been on campus. Not to mention the fact that SJU nor can any school control what anyone does on their twitter account.
Yet you are going to hold SJU responsible for what John Smith did? SJU's response is simply, "We don't control John Smith, we don't know who John Smith is, John SMith does not represent SJU or any part of our school, how in the world is his tweet OUR fault?"