>The worst loophole is what Redhat is exploiting
I do wish people would stop describing it as a loop hole. However unpopular their behaviour, we all have the freedom to not do something. It'd be a pretty dystopian world if anyone or any organisation could be compelled by someone else to forever continue to act in a particular way, if they had chosen to act in that way once.
Just imagine the consequences. You write some software for a lark, and publish it just once as OSS under some license or other that "solves this weakness" in GPL. You then decide not to continue public work on it. You then get sued, because some member of the public had picked it up and wanted the new version's source code that you'd given to only your mates.
"All" RedHat are doing is deciding who their "mates" are by means of monetary exchange, something that GPL explicitly permits. I put "All" in quotes because it is a pretty large dynamic range between software written for a laugh and a seriously large enterprise undertaking, but it is all on the same spectrum. If you want the laws of the land to protect oneself from undue abuse at the small end of the spectrum, you have to accept that they apply at the other end of the spectrum too.
Fortunately, the safeguards in our modern liberal democracies mean that no one can be obliged to do something by anyone else. You don't even have to act according to a judicial order if due process even got that far; you can choose to take the consequences.
I also note that Perens seems to have lost his "opinion" that he gave sparking off the fuss with GR Security, which ultimately seems to have done them no harm whatsoever. I always thought it ridiculous that he took a swipe at them. Seems he's unwilling to take on IBM's bigger legal budget.
If there is fault in any of this, it lies with "experts" who for years have been saying that GPL is solid, have actively encouraged software developers to release their code under the "safe" GPL, but have turned out to be wrong. This has no doubt occurred due to flawed engagement with lawyers, a failure to explain to them adequately that "software" means more than just one specific version of the source code text.
Solutions
There probably aren't any bullet proof enforceable copyright-based license solutions without contracts and monetary exchange.
The best way to go is to take away RedHat's market.
The way to do this is for the Linux kernel project to fork RedHat's contributions, back a different distro (Debian?) as the official "this is Linux" combination, don't distribute a binary of the result to any *.redhat.com or *.ibm.com domain and to ask that any remaining down-streamers refrain from distributing to those domains too. That will mean forking SystemD, Gnome, other such things too. Beat RedHat at their own game. If no one distributes binaries built from this mega-fork to RedHat, RedHat has no rights to the modified source code even if it contains some elements of their own work. If a down-streamer does distribute to RedHat, cut them off from new versions too.
RedHat's strong position today is because they unofficially and without opposition put themselves into the role of "this is proper Linux for the serious minded". If the community doesn't like what they're now doing, the community does actually have the ability to appoint themselves in that role. Not doing so is simply acquiescing to what RedHat is doing. By offering a strongly coordinated "official" alternative, that's the best way of getting users to migrate away from RedHat's flavour of Linux/userland and take their market away from them.
Why This Could Work
RedHat would still be able to claim, "our's is the best Linux", but if the kernel project was closed off to them it'd become increasingly difficult for them to sustain that line.
For example, to where would a new lump of code to support the latest X64 chips go? The official kernel project, or RedHat? That would be the choice of the person(s) writing that code (or their employer), but at the moment no one is asking any such people/companies to make any such choice. It would be a battle of wills, but if successful then within only one or two chip generations RedHat's Linux could become massively obsolete, slow and inefficient.
Admittedly that's a big challenge to organise all that, convince everyone to go through with it, and a bit of a gamble. But, if it worked, RedHat could be out of business within 3 years. The mere threat of this outcome might be sufficient to amend their behaviour.