Really? I have no memory of this. I must have missed it somewhere.
Though I don't necessarily think that would preclude a storyline centered on Nasher from working, or even getting NSFW. Asexual and Aromantic aren't the same thing, and it's my understanding that some ace folks find fulfillment in sex as a means of bonding. Could be I've been mislead, of course.
If it's specifically stated that he's Aromantic, that would make it much harder to work.