That is almost certainly reference to several open source projects where building the thing from source and distributing the resulting build artifacts is "legal

That is almost certainly reference to several open source projects where building the thing from source and distributing the resulting build artifacts is "legally problematic" because of trademarks. In the 00's this was giant issue for Mozilla(TM) anything. If I understand it correctly there is some kind of related issue with for example "OpenShift(TM)". On the other hand it somewhat seems that most projects learned from the mozilla shitstorm, at least looking at the amount of "foo"s with open core "foo-ium"s. The point there is that whatever sourcetree that the version with trademarked branding gets built from should be fork of the branding-free opensource project, not the other way around.