@dhein meta.se has some posts on enforcing NDA's, or copyright, that might interest you: https://meta.stackexchange.com/questions/94465/should-moderators-enforce-ndas-for-software-vendors/94488#94488, https://meta.stackexchange.com/q/19508/369802 and https://meta.stackexchange.com/a/195875/369802 make some interesting points.
But yeah, the outcome of all those is sort-of the same: It's quite futile to mention it. Plagiarism can be moderated (and flagged/commented), but copyright is something we don't touch :(