Hmm.
Which shall it be?
1) Strong enough sense of self or duty that he can do this without being a BL-type
or
2) was unaware or hiding from himself that he really is a BL-type?
It's not tagged Yaoi, and there are indications that he and the mangaka he is being an assistant to are interested in each other, albeit still in self-denial of this. And... it is tagged as romance, and as comedy.
The comedy is definitely there. And... as I think I'm seeing hints that the author and her assistant are interested in each other, that would support the romance tag.
So I really hope that it isn't #2, as that would indicate mistagging.
And this early in the story, that would have to be deliberate mistagging, not just a lack of knowledge about where the mangaka was ultimately taking an ongoing project.
Oh, I must say that the art style really does mesh well with this story, in my mind. A very good fit.