I quoted this line because I think it captures something most white people often do not question. If you are white, you probably do not ever worry that your race makes you less welcome in outdoor environments and clubs/groups. The author is saying that POC on the other hand do not feel this intrinsic sense of belonging. And it’s not just the literal physical space of a hiking trail — it’s the community / group spaces like the GMC, like a subreddit for hiking and appreciation of the outdoors in Vermont. I can’t imagine something that screams “you don’t belong” more than being told your feelings and perspective are stupid and invalid, which is what a lot of other commenters are saying.