OK, I don’t hunt, but I don’t think anyone is saying that the hunt (via the master or the secretary) doesn’t have the final word on who may or may not join them, for any reason. To maintain their club and their land access they are free to turn down anyone who sounds fishy or who they cannot accommodate for any reason.
That said, any time you open your mouth you are at a minimum representing yourself, and often more than that. I don’t get to be rude to my clients at work, even if I consider it deserved, because in doing so I would be poorly representing my company, in addition to myself.
Wanabe represented himself as kind of clueless.
The master represented himself as rude, and as a representative of hunt, represented his hunt as unwelcoming too.
Since he doesn’t want Wanabe hunting with their hunt, perhaps he doesn’t care about Wanabe’s perceptions of that hunt. However, in the long run, he would probably serve his hunt better by being more diplomatic. The horse world is small and incredibly talkative.