As the comments have indicated, this is a judgment call.
Rabbi Moshe Feinstein allows a synagogue to give an aliyah to someone who does not personally practice all the mitzvahs (though he writes it is not preferable). (He feels that the card-carrying Reform rabbis of several decades ago, however, did not believe in the sanctity of the Torah being read and thus can't receive an aliyah.) He has another responsum about the prohibition of flattering sinners, where he concludes that giving synagogue honors to a sinner is not an automatic declaration of "the fact that you do Action X is totally fine by us."
Nonetheless I think it's within a synagogue's rights to make a statement that certain actions so beyond the pale that they preclude honors. (I suspect many synagogues would, for instance, give an aliyah to someone who doesn't observe shabbos, but not to someone intermarried. It's not a halachic thing per se, it's a public-policy thing.)
In your particular example, I suspect there are several reasons why a synagogue may choose to make a statement: the sin is universal for Noahides; its acceptance in both general and traditional-but-not-Orthodox society is relatively new; and it's perceived that sometimes the sinner (or a movement with whom he is perceived as affiliating) may have more of an attitude of "your religion is wrong so go jump in a lake", compared to "eh I don't live up to all the laws."