I doubt they'd make a different vampire race for one character. It's like the fact that the akaviri are all imperials in oblivion. Especially since Movarth is pretty much an easter egg anyway. There are so many other things wrong with him, such as his random race and sometimes gender (he has a male breton name). Having orange glowing eyes is the least of the plot holes here, but like I said the same thing happened with the akaviri at pale pass, only in this case it was an even smaller incident.
One character? there's more than that.
Hell, a lot of vampires in Skyrim exhibit The Order's traits and as Werewolf&Vampire said before me, the Clavicus Vile cult would be some.
As well, at least the akaviri warriors in Pale Pass could be excused due to the fact that they could be akaviri or transformed tsaesci, as I've
detailed once in a thread before. The volkihar are all over Skyrim, their subsequent transformation of what could be cyrodillic vampires, is odd.
Lastly, Movarth Piquine's is hardly an easter egg. An easter egg is like finding a sentient drunken troll drowned underneath a bridge,
leaving a note that no one will pay his toll, so he'll commit suicide. That references to the story of Billy Goat Gruff, not another ES game.
The quest that Movarth Piquine is involved in is actually a properly detailed quest within the game and not some hidden reference.