Oh, he will- with or without Emet-Selch's permission. Though having him act so compliant feeds Hythlodaeus' ego a little, and he gives his cock a squeeze before letting go briefly and pushing his own pants down further so that he can start to rut against his behind.

"I could simply use you this way." He hums as he thinks on it. "It would be what you deserve."

Knowing that Hythlodaeus was getting off and he wasn't, maybe that would be a good punishment... and yet despite considering it, he keeps Emet-Selch aroused by fondling him lightly.