If true, it was a childish, irresponsible stunt and the burn will last a long time.
Do we have a record of the negotiations or some reliable source?
It doesn't appear Poe actually said the FC moved the goal posts, but perhaps worse, the FC has not yet clearly denied it.
In any event, it appears Trump is needlessly burning an important bridge.
Unfortunately, the link you provided elsewhere on this thread did not quote Poe as saying "the goal posts were moved". Instead, the article gave the reporter's version of the narrative. That of course, is not compelling or even persuasive evidence.
However, drilling down, the Fox and Friends video of the Poe interview reveals Poe actually did use the words. The problem is whether he did so incorrectly.
Most of us would apply the term only where the party accused of the "moving" did so after its final offer was accepted.
Importantly, Poe does not distinguish in this regard whether it was a post-final offer "moving", or simply continuing negotiations. He does mention that Ryan continued to make a few concessions (whether bargained for or not??) and does not mention Trump playing a principle role in the disscusions.
The question remains whether the FC by its statements was at least morally bound to accept Ryan's bill as last revised, or was yet free to continue negotiations.
I think it very likely if Trump displayed disatisfaction with the FC over the status of negotiations, that Poe jumped ship.