I'm from the north west Highlands (not Knoydart) and I would say that the vast majority of people just roll their eyes at the trans stuff, probably haven't read much about it or been interested in it. Some younger people are, obviously. My guess is that the Knoydart Pride festival was started by an individual/s who were very enthusiastic, and others in the community aren't bothered/are happy there's a party/are supportive of their neighbours.
I know a handful of people who are vocal/proactive about homosexual rights and/or trans "rights", and without exception they have all moved into the area and brought their ideas with them! Which is fine, but it doesn't change the fact that the indigenous population is more pragmatic about things. There are plenty of gay people locally, but they just crack on with their lives normally as we all do. I don't know any trans people in my area (although I do know two who stay outwith the area).
What I'm trying to say is that Knoydart Pride is not representative of Highland communities, no. But I don't know what that has to do with a Harry Potter Halloween party. You'd think if all the folk of Inverie were fierce TRAs that they wouldn't have planned a Potter party in the first place. I strongly suspect the harassment has been coming from people unconnected to the community, who just object to anything Rowling related anywhere, whether it affects them or not. A shame.