Everyone who's finding fault with the idea that he might blackmail her, betray her and whatnot seems to be forgetting that she basically enslaved him and, while she isn't the one who destroyed his kingdom, she is a bloody-handed conqueror just like the people who did. Further, she has threatened him with death repeatedly, both directly and via her lackeys, as a consequence for the slightest semblance of trying to think for himself or fail to do whatever humiliating thing she might order. You can't "betray" your slavemaster.
He owes her no loyalty and the only weapons he can use are the weapons of the weak. It's easy to be straightforward when you can straightforwardly order your 100,000 troops or whatever to destroy anything that annoys you.