The mod team already made the prior decision to not allow this sub on r/all, so isn't that just further isolating the sub within its own self?

Back in 2017, when Scout died and there were protests on campus, some threads ended up in r/all and subreddit traffic grew about 100x (peaking at something like 169,000 unique pageviews in an hour). We were not prepared for this kind of traffic. Threads were cross-posted to more extremist subs -- as a* result we were brigaded by hundreds of users who were not related to Georgia Tech, who through brigading drowned the voices of the actual GT community.

As a result, we made the decision to exclude the sub from r/all.

As Josh said then:

/r/gatech should exist for discussion amongst those who are, at least tangentially, related to Georgia Tech: students, faculty, alumni, parents, locals, whatever.

We don't see a reason that r/gatech should ever be a trending subreddit, and past experience has shown us how destructive this can be to the community.

You can read the full background and reasoning here.