Having stupid petty arguments with your peers is good for social development and gets you used to using rhetoric and standing up for your beliefs in a low-stakes environment. None of this is occurring to Popp, of course.

He does notice that Sephiroth is getting engaged in the argument and this means that he's paying attention to him, which he's on some level happy about because he... likes... attention... but also he's still in a real snit about the whole premise of the argument out of his pride as a mage.

"Oh yeah? If you think using magic to bake is so easy, why don't you try it?!"