No, they are harassing a person who is exercising their right to associate with whomever they want.
To associate with, that is the part that matters. Not "to be associated with", which is what people in a mob think is what matters, even though it does not, certainly not enough to give them license.
Harassing is carrying a _ton_ of load, way above its capacity, in the essay. I'm very curious for your perspective on what incidents were harrassment.
There's a certain motte-and-bailey aspect in my read, the narrow claims are their talk on Geoff's work was not accepted at an academic conference and someone removed Geoff's name from their paper.
The broader claims range as petty as the conference added a non-standard tricky clause to harrass them and engineer the denial of their proposal, before their proposal was made (?, also, it's a bog-standard morals clause in my read) and as vast as you must allow anyone to associate with you & it's immoral to decide who you associate with unless they've been convicted of a crime by a jury in the United States.
It suffers from its rigidness and righteousness.