I guess,
IANAL - I'm just trying to engage the guy in debate and see what shakes out, without using the blunt tactic of grabbing him by the nuts first (to be sure I get his attention)
Who knows, he may reply with a good reason why there are no copyrights attributed to Mitel and elsewhere in 'his' stuff and not be interested in being part of this community - he's more likely to be interested in us if we are approachable than if we yell and point excitedly.
Besides, the only other comment in his forums was a 'spoiler' pointing back here.
But, getting back to the point, does he have to release his GPL source to the public? I'm not sure I agree with you having read this:
http://www.gnu.org/licenses/gpl-faq.html#GPLRequireSourcePostedPublicBut if you release the modified version to the public in some way, the GPL requires you to make the modified source code available to the program's users, under the GPL.
I think its a little ambiguous either way, I still find myself erring on the side of, yes I think he does rather than no, only to the people who bought it from him.
As before, IANAL, and the copyright issue does seem altogether more clear cut .... I'm interested in seeing whether he replies and how he views his position re the GPL and copyrights.
As for the Linuxon guys, I don't know - they seem to have done less customisation, although the copyrights seemed not to be visible in the screen shots (although the GPL was).
Regards
David.