Earlier quoted context omitted.
Imho, try to keep it from going mainstream. If there aren't enough viewers to make advertising profitable, then many of the problems filling the current internet would not appear in the first place.
Gatekeeping then?
More like not pushing for more acceptance. Allow a community to form, but do not try to market your way into a larger community.
Obviously this approach is not sustainable, at least on the first try, as the Internet itself shows.
However, now that the internet already exists, a parallel internet so to speak would not have as much/any appeal to the average consumer/corporation, which ideally would lead to only those who are interested in the community/content arriving there.