No, they actually play it down a lot. OP is a compilation of rare hints that show the full picture. The hints are rare enough for normalfags to forget, and additionally, they mix in a few lies such as "we hug our parents more often than each other" to confuse the normalfags, giving them an alternate story to apply their confirmation bias on.
Fuwawa is allowed to leak out her siscon tendencies, while Mococo has to act tsundere, as if it's just Fuwawa's weird siscon joke and there's nothing behind it. Behind the scenes, Mococo is completely willing (based on the big picture). The few hints of Mococo's willingness is the part about sitting on Fuwawa's lap as well as this part, which pretty much confirms them hiding things:
https://youtu.be/2hLYCZDHMw4?t=12795 