I get the feeling that (unsourced) article is not telling the whole story.

It says that a family member of Allen's would not let Gorley in. And that the hospital (in their statement) implies Gorley "[became] disruptive to providing the necessary patient care," so they "involved [their] security team to help calm the situation and to protect [their] patients and staff" by removing Gorley. Their version.

They could have been mean-spiritedly discriminating against Gorley.
Gorley could also have been creating a disruption that got him kicked out. And I've never seen Missouri as a place that endorsed or recognizes gay marriage.

For all my dissent from your opinion on these matters, M E M, and my broader dissent from gay marriage, I don't endorse keeping a gay man out of the hospital where he could give encouragement and comfort to his gay friend.
And I seriously doubt many hospitals would similarly exclude gay friends, particularly if, as the article says, he has power of attorney for Allen. G-man could better extrapolate if power of attorney applies in a state that doesn't recognize gay spouses.