At this point I'm thinking he was impotent due to an inability to be emotionally intimate with a partner. It seems like he would cover for this issue by saying that his sex work made him lose interest in sex. Meanwhile, he probably could experience his sexuality through indirect means like *advertiser censored*, or super-kinky sex (rather than loving intimate sex). I've seen this before in someone who was a lot like Luka and had a similar background; they want to love but they don't know how to have an actual healthy loving relationship. Instead, they keep going back to these distortions, these methods that distance them from intimacy and are oddly comforting to these people because the pain is what they've always known at home. It's similar to self-torture--self-cutting and the like--where there's a relief and comfort to pain. And I believe this is because these people knew more pain than love growing up.
Of course, I can't prove this and neither do I want to write a book, threading all the biographical details together about Luka, just to prove this point. But it's a strong hunch at this point that he was definitely impotent and it was due to emotional issues stemming from his upbringing.