Sure, but physical intimacy still makes him uncomfortable at this point in the game, which would make him a good candidate to focus more on the emotional aspects of a relationship with. As of now it feels like he's pressuring himself to "bounce back" a little too fast, possibly even to please Tav. And ace doesn't necessarily mean complete absence of sex either. I just think it would fit to take it more slowly and build emotional connection before engaging in physical intimacy. Which also includes saying no to the initial invitation to sex in a way that doesn't break the romance.
With a lack of other companions to pick for this, Astarion is sort of the most logical choice for an ace/demi romance from the companions we do have (in my opinion). Possibly Wyll too from what I've seen of him, but I haven't even romanced him in the game to really know what he's about. Just find him so incredibly boring unfortunately.
