As for copyright violation, there's been planes pulled in the past from the official FG repository for the same reason....
The only plane that has been pulled I'm aware of was the Honda Jet and that was a question of trademark protection rather than copyright violation.
Mistakes happen.
Sure, they do.
Only, replacing a license text which does not read GPL by one which reads GPL can't really be seen as a mistake - it's hard to imagine anything but intention.
Nothing immoral and most definitely something desirable has been done by distributing on Fgmembers....
We might disagree on that one. You lament the misuse of GPL-licensed content in this thread, yet you advertize a repository which does just that misuse. You argue for the freedom to bundle GPL with non-GPL content, yet you advertize for a repository that most definitely does not even recognize the theoretical freedom to do do dual licensing or bundling. Why don't you discuss your ideas with Israel and see what happens? Do you not know, or do you just not care?
We all publish GPL in the hope that the majority of people makes good use of it - i.e. uses the content, adds to it and makes something come back in some way. At the same time, we hope that we don't run into people who just take and re-distribute for their own benefit. Every time we run into the likes of FlightProSim or FGMembers who do that without a shred of respect for what the original authors intended, I guess most of us doubt the decision to publish GPL.
You argue 'legal' when it suits you to do what you want, you uphold respect for the developer when it suits you to justify other things you want, you uphold respect for the user when it justifies yet other things you want - only it never really goes together.