Specific Sinbad/Ja'far shipper, let's talk about priorities.
You seem to have these things completely backwards.
Thing you warned for: Ja'far, the shorter, slighter character on the low end of the relationship's power imbalance, acting dominant in bed. This came complete with an apology to the reader, and reassurance that it would all be okay because he's still the one getting penetrated and not penetrating.
Thing you didn't warn for: Consent is apparently a completely foreign concept to both parties, and this is played for laughs.
And yes, I know that canon has its own problems with not taking sexual assault seriously (that is another rant for another comm). That is not an excuse for fandom to do the same.