Well I think it's not nice to name people on forums and Gulfjet is the worst example you could name. I would even say that your friend should have spotted the management which has more to do with circus than aviation. It's easy to blame the company but when you deal with such bad ones I wouldn't say your friend was very smart on that move. Before signing you have to do your homework. Sorry about that.
If the aircraft owner didn't pay Gulfjet for some time, I understand they might have some problems paying salaries of crews operating managed aircrafts.