The Professor lets the Mycologist have his fun. There's such an allure in the way he moves, the cause of which is confirmed with that last sentence, that made their forked tongue flick as if to prevent outright laughter. If the Professor saw him truly out of his element would take the lead again, but right now this is exactly the desired outcome and fantastically performed. Even if there are some collateral damages...

"You know how the saying goes, dear..." taking advantage of a rather bold change of pace, the Professor lets themself "fall" in the right angle for the Mycologist to grab without even breaking the song's timing, was he so inclined. In that case, the answer would be:

"Adapt or die~" with a delighted fanged smile.