I am aware of all these facts. (Matter of factly, I am demi-sexual myself, which is sometimes considered as part of the asexuality spectrum, so I dare say I am not entirely uneducated on such matters.) As you say, all this traits can occur in asexuals and as such do not necessarily hint at a wish for sexual intimacy. But in my posting I didn't look at each of them individually, but rather as parts of a bigger picture. Taken in context of both the narrative and of Markus' personality, my takeaway was "conflicted/afraid" rather than "disinterested". There is a broad spectrum between asexuality and more typical sexual interest, after all. I should know.
Of course my interpretation of Markus might be wrong, only the creators can clarify, and they probably don't want to. Nevertheless, I would appreciate it if my opinion weren't treated as the result of ignorance and lack of education. (Though my rather hazardous grasp of the English language might admittedly suggest otherwise. It is not my native tongue, please bear with me.)