Comment you need to do some homework first (Score 1) 151
It is no way certain that there is any GPL violation here. Don't bother until you find one. I mean don't yo feel bad everything you hear about some site getting take down notices for reasons that prove unfounded? I wouldn't want to be like that. So really you need to find evidence in the binary that source code submitted by someone outside of MG and CS was used to build the closed version. If you find that, then you need to contact that person and learn whether or not they have the rights to that (could have been work for hire with a contract or they could have done a transfer of ownership as part of the patch submission process for example) and even if they care at all about it. Why might they not even care? Well MG could just say, "oops, thanks, here we have removed the offending source from our build, here is the new closed version that complies." And really unless you want to be a jerk, that should be good enough. You yourself wrote that you don't want to be that jerk because you do not wish to give ammo to decision makers to avoid going open source or GPL even in the future. So is all the work you and others will need to do worth that potential outcome? That's up to you. Just find an archive of the GPLed version and go from there for the future is what I personally recommend.