My thinking precisely! This whole notion that all characters who have been fucked by other characters can no longer be fucked by the MC is antiquated and trivial, not to mention contradicted multiple times. DPC doesn't give a shit about the anti-NTR brigade anymore and he's been testing it out since the start. He made it seem like he was bowing to the pressure but we have multiple instances where characters are implied to be sexual with other known characters yet Fuckface has been plowing fields wherever he chooses to sow. The explicit implications are yet to be acted on, though I believe it's only a matter of time. I think that further advancement of certain characters' lewd scenes will depend on how easily incorporating them into the storyline is.
I may be touting my opinion as fact but that is only to provide evidence for my point. My point being; there may be characters that we'll never get further (or any) lewd scenes with but it won't be because another character fucked them. If DPC can have the MC fucking Heather and have it make any sort of sense, you really think he won't do that and miss out on all the useless dramatic bullshit he can conjure up from that?