He likely doesn't have as much overall romance-related content compared to the other companions, but he's still valid.
I romanced Beast twice, once early on and again after Larian made all their changes to the game. The first version was... not good. It felt like Beast got
half the content Ifan did, plus his personal quest, like pretty much everything else in Arx, seemed partially unfinished. Larian did make some serious improvements, but in the end, Beast's romance still didn't reach Ifan's level, though at least it's... okay now.
