Yes. Just like it would be with Goo or any similar change in morphology.
Here's the thing about goo, naga and similar undulatory monsters: you don't have to create a completely different sex scene for it to make sense for them. So long as the PC retains everything from the hips upwards, and Fen was sensible enough for that to be the case, they can have the same sex scene as two-leggers. Yes, it's a bit of a fudge in some cases, and their existence means you can't do too much interesting in the leg department without investing a lot of effort, but still; you can give them access to general content without it being too egregious.
The entire problem with centaurs is the genitals-on-the-back thing. That cannot be ignored without it standing out like a sore bellend. Hence having to write almost twice as much content, just for them.