If this is in fact dead, it is literally, absolutely and exactly the closing of a loophole, whether you like that or not. The T&Cs have always been pretty clear with respect to what the credit can (or cannot) be used for.

We actually don't know that. As has been stated (several times) in this thread, its also quite possible that given significant technology changes that UA has been making to their back-end systems, largely to support enabling announcements that were made just today, that UA actually changed how these transactions are coded and may be in fact be who "closed the loophole" (as opposed to Amex). Have you considered/acknowledged that possibility?

Well, that is your opinion, but it has absolutely, positively, nothing whatsoever to do with the Terms and Conditions of the benefit that Amex presented to you when you applied for the card, and which you willingly accepted.

Just coming into a forum and emphatically declaring how this "should" work, does not, ipso facto, make it so.

Regards

P.S. For the record, I've always used this "loophole" to great personal benefit over the years, but I've never considered it a "right" and I've also been very clear eyed that it could disappear at any moment. Honestly, we are lucky it lasted this long (again, assuming it really is dead)