If someone from a league told me to leave the park because it was league night, I would tell them to go Chuck themselves.
I appreciate how much work the various leagues and clubs put into maintaining the parks, but the parks are still "public" parks and everyone deserves a right to play. League players should be ambassadors for the sport. They should be friendly and encouraging, not confrontational and prickish. There are already enough elitist dicks in the world.
A big reason I love disc golf is because of all of the cool people you meet on the course. Usually everyone is very friendly.
Just one man's opinion.
sounds like a tough guy response - I have played in league play on and off since 1999 and every time we came upon a rec/casual player we simply said something along the lines of "hey guy(s) its league night and you are going to find large consistent groups of players on every tee, just FYI" along with "the other courses in town will be very open for play"...
Most of those casual players are really cool about it and dont want to spend another hour finishing their remaning holes either....
you obviously don't seem to be that type