Maybe he didn't get it up and she just rubbed herself against him. That's how I read it, anyway.
Grayson's own interviews pretty clearly indicate it was sex, and it was against his will.
I see Tarantula more as a card-carrying villain by this time.
And yet, Grayson's own interviews go out of their way to rationalize why she's not *really* a "rapist," even though she had "nonconsensual sex" with Dick.