"Are there other distributions that have a similar policy and a similar integrety in sticking with it? I was suprised to find that Gentoo's social contract, despite being originally based on the DFSG, leaves this point out."
Hmm, I wasn't personally aware of this particular clause. I'll be ruminating on it. As far as I know, Fedora doesn't have any special Fedora only licensing terms with anybody.. including Mozilla. I'll probably start a discussion about enshrining this clause or something akin to it in Fedora's policies.