The licence is a defence.
Plaintiff: "Defendant is using my copyright content unlicensed."
Defendant: "Plaintiff licensed it under GFDL 1.2 Or Later, and I'm
using it per GFDL 4.7, which is covered by Plaintiff's release."
Plaintiff: "But 4.7's not in the same spirit as 1.2!"
I can't see this flying.
They'd need to bring an action against the FSF and have it stick
before they could put those reusing under an "or later" provision in
serious danger for doing so in good faith. I would think.
What action could they bring against FSF? The only claims I can see
being relevant are claims of copyright infringement or contract
violation, neither of which would (directly) involve FSF, since FSF
doesn't own, or use, any of the content, and they are not a party to
any of the contracts. The only way I can see the "same spirit" clause
being enforced (and if it isn't, FSF could do whatever they like with
anything released under GFDL, which would be very bad) is if it can be
used as a counter argument for the defence you describe.