That "someday" may mean "tomorrow" if Dante catches wind of it. Granted, he agreed to not threaten anyone with violence, but he could threaten them with other things. He's creative like that.

In the meantime, Dante was actually happy to see that Nelo had a hobby. Everyone needed one. Granted, he's slightly offended, because his cooking was just fine dammit, but he's keeping his mouth shut. For now, back up because his brother is smiling.

"Hey. Can I ask you a question?" He keeps going without waiting for an answer. "Who are you, and what have you done to that guy that showed up here a while back?"