Make no mistake, OD is GPL, and will be for at least the first version. AT LEAST. What happens after that is anybodies guess at this stage.
As for Q2Admin, I think we already looked into that and found it totally lacking for what we needed... I *THINK* it was that anyway. There isn't really any open source anti cheat stuff out there thats perfect, granted, which is why we are making our own that will be updated withen the game rather than needing third party support. Last thing we want is bloatware or something we can't control directly.
It's not something up to you. If you used q2, doesnt matter that it's almost rewritten, you still have you keep the new codebase GPL, unless like friar said ditch q2 completely and make your own custom engine. Then you can make it as closed as windows 7 64bits edition. Cheats will occur whether the engine has its code open or not.
Not true. If we pay for a licence, we can keep it closed sourced, simple as that, which was something we WERE and ARE looking into, and that hasn't changed. I can't tell the future on OUR project, so neither can YOU. But I never once said it made a difference how much was rewritten in the code, in fact I said the complete opposite, and would never cheat anybody out of anything.