Well he hasn't gotten his revenge yet. And didn't you read? The uke was seduced by him and did almost all his work. And that guy took all the credit and started treating the uke really bad. If he gets another guy or falls out of love it doesn't matter. That's normal. But why was he treating him like a toy?
And the uke now isn't taking his revenge. He's just treating the lazy incompetent junior like he deserves.
I wonder how he'll actually take the revenge though. Yeah revenge for love does kinda seem cringey but the seme is nowhere near innocent. So it's good