Gen didn't mind that he's being laughed at, he's behaving rather pathetically, honestly. But he can't make himself stop. What -

"- But he doesn't like people, like that. That's the whole ..." Gen flailed his arms. "... How did you get on this topic anyway? Why - why did you ask me about it?"

It seemed impossible that Senku might've mentioned him in this context, but it seemed the most likely explanation at the same time.