This is such a lazy way to hand-wave my criticism. Any developer, whether it's L&P or Dr. Pink Cake, or Mr. Palmer, is responsible for planning out and executing their game. Pointing out the flaw isn't the problem, the problem lays with L&P for fumbling the end of PD13. Can you seriously look at Part 1 and 2 and think "there was no way to avoid this."? He should have seen this coming from a mile away.
I don't think L&P has any problem writing erotica. He isn't delaying or stalling out of any sense of bashfulness or discomfort over the subject material; he's delaying because he's trying to create a sense of anticipation and suspense (and that's being generous, many would accuse him of far more nefarious reasoning). But that desire to prolong the suspense is in contrast to a story that can't justify any more prolonging. L&P is afraid that, once Sophia has sex with a character that isn't Liam, that a certain sense of anticipation and titillation will be lost. He wants to build the tension as long as possible to maximize the effect of when Sophia finally has sex. He's making a business decision more than a creative decision.
My theory is that he's struggling to find a reasonable way to prevent Sophia and Dylan from having a sexual encounter, NOT because he's nervous to write smut, but because he's nervous that it will hurt his long-term profits. Once that cork is popped, you can't bottle it back up. But because of how he's structured this update, he's struggling to find a coherent way for Sophia and Dylan to move their relationship forward WITHOUT it resulting in something overtly sexual. The bath in part 1 was very sexual, but it kept a thin veneer that Sophia could pretend it wasn't sexual. It was flimsy, and silly, but fine ok. But if Dylan and Sophia's next encounter has to exceed both the bath tub event AND Sam's actions in the hot tub, then there's no way for Sophia to pretend it isn't overtly sexual. And once that happens there's no going back. The idea that we are still YEARS away from the first sexual encounter doesn't seem feasible any longer.