But that at lower energies the same mathematics exactly describe general relativity. Thus from that perspective, it’s a pretty good theory.
Granted, but I'd call that a weak confirmation, not near enough to graduate from hypothesis to theory.
Indeed, to the degree it can't be tested or falsified, it doesn't even qualify as "hypothesis".
A better term would be "educated speculation", or less politely: S.W.D. (scientific wet dream).