Some people will take advantage of what we give to them. To accept a gift once is one thing, but to continue using and abusing the same thing over and over without ever asking again is a whole other story.
There is no way to justify it; it's obvious that this friend didn't mention his rooftop use openly because he knew it was wrong. This attitude only worked against him because if he had asked again, his friend would've probably said yes.
This is simply a disgusting attitude, and my advice is to never act this way, because if you already have a generous friend, it makes no sense to take advantage of him by secretly using his stuff. I suppose this was motivated by shame, because he likely was pretending to have a lifestyle he didn't have, but what a waste of time.
He was also warned before being revoked accordingly, so his reaction doesn't make sense either. What irritated me most as a reader is that when things went down, he reacted angrily instead of being apologetic. That shows you a lot about someone's character and how entitled they think they are to someone else's property. It's insane if you think about it, but there are many people like this walking amongst us.
Either way, as I always say, the information OP gathered thanks to this incident is incredibly valuable to adjust the access some people have not only to his rooftop, but to his life, in my opinion, but you'll be the judge of that.
Do you think it would've been better if he talked to his friend more deeply before revoking access? Or did his attitude express everything he needed to know?