Red Hat's behavior is not any kind of loophole in FOSS licensing that's worth worrying about. It's just a shenanigan they are pulling because they think it will help them stay paid.
The loopholes worth fussing about are SaaS (peple having absolutely no control over the software because they are using someone else's installation remotely) and tivoization (locked down hardware preventing users from exercising their rights in regard to the FOSS operating system it runs)
They don't want to pay their engineers to work on Red Hat only to have some free forks follow the work, so they came up with the idea of eliminating and likely blacklisting customers who look like are there just to pick up changes for a fork.
Red Hat should be applauded for trying to find a business model which is compatible with copyleft, yet prevents freeloading.
Stallman never wanted to create a license that was anti-business, that's why this kind of thing is possible. A license which says you cannot drop or blacklist customers for any reason wouldn't be a free license.
There is an abundance of distros out there; anyone who doesn't like Red Hat for any reason can easily use something else.
It will be interesting to see whether Red Hat's ploy works out in the long run. Will it help grow their business, or will it turn out to be detrimental due to a backlash effect. Obviously, some people don't like it; it's a question of are there enough of them to matter.
There is also the question of whether a free fork of Red Hat that people can develop and test with without becoming paying Red Hat customers really is bad for Red Hat (as they are obviously convinced) or whether it is actually good.