I am inclined to think so. It was a hassle to use the original link. The one from this article works without a problem.
Since I do not pay FB for their product (other than offering opportunity for them to gather data) I reckon they have latitude to black list or block at will.
I'm sliding toward thinking they are a monopoly that should be broken up, unless they abide by freedom of speech guidelines. I'm not quite there yet.
It would be interesting to see what happened if you posted another link to https://amgreatness.com/. I would do it, but I don't have a Facebook account. If they are being blocked by Facebook, American Greatness might want to know about that.