I don't think anyone in the field is triggered by some guy pursuing his interest in aliens and UFO.
What they get triggered about, is that guy using his relatively large platform to say that anyone not agreeing with him is part of the establishment or otherwise useless, or to say that there is no other possible explanation to a certain phenomenon than aliens, or to be insulting to another colleague during an online talk.
When did this happen? In the podcasts and interviews I heard, Loeb was often provocative towards the establishment, but I never saw him make negative comments about an individual.
[1]: https://www.forbes.com/sites/startswithabang/2021/02/16/watc...
[2]: https://twitter.com/whereisyvette/status/1360771406661881857...
If anything, I would say the annoyance is that for the department head of Harvard to be spending his time (and seeking fame) on topics like this, instead of using his position to 1) further "real" research, 2) address problems in the field, 3) in general, make more of the role he has, is something of an insult to people trying all their lives to reach such achievement.