Rogan has been a shit commentator for years now.
I actually think, though, that him asking Leon about the father comments actually worked against Covington. I think the crowd sympathized with Covington when they saw how genuine Edward's comments about how it affected him were. Then when Joe interviews Covington, the crowd that had been loudly in his favor all night were suddenly loudly booing him. Of course most of the UFC live audience are drunk I assume, but I'm sure some of it was a real distaste for Covington's schtick going too far.