Oh, if there were a "No Horde" statement, it would still exclude Tauren to a point, as they have had a long bond between, and it only got shaky due to the existence of Garrosh. Gorgeous art. As well, Bel'ameth has a different lore aspect compared to Silvermoon, after all.
Yeah def, like I am mostly joking (I seriously need to finish this art, its still a WIP) and I do have a lot of Horde/Alliance pairings that would have issues seeing each other across factions but that is a problem I solve in writing with myself of course 😔
Hey. We gotta have room for our own world building too - though, you should finish it, the art. Haha. In the case of cross factions, the Tauren and Night Elves have been the best pairing for a long time.