Way too much information at once. Tony had to hold his hands up to stop any more of this abuse and try to compartmentalize to even begin to respond. There wasn't a quote history unquote with Wanda and, assuming, hypothetically, that there was, then there would be no reason for him to have to imagine her in any style of titillating costume because he could probably get her to indulge them in the case of their history being so rich it bore expressing and that was only assuming that their history was so ancient that he was bored enough of un-costumed Wanda or even the Scarlet Witch to need to role play which he was sure no one could ever be. Jessica, on the other hand, as Steve so helpfully pointed out, was off-limits, which made every fantasy that much richer and filthier and Steve really had no idea what 'off-limits' was like and, and here Tony deviated, the finger he had held up to start his first and thorough point being retracted and his hand spread across his chest instead, it was really not worth taking the time to explain it to Steve. He didn't need to know about...inappropriate fantasies.
"It'll slow her down," he pointed out instead. She couldn't accidentally adopt. That only happened once a decade when a kid happened to fall out of another dimension and she couldn't have both ends of it. "And we can intervene, without some... sticky-fingered, chronic masturbator claiming he can't pay child support on welfare." As much as Steve thought otherwise and believed what this wondrous future world could make real, Cassie being a lesbian would be a relief.