UA may have a special arrangement with Lavin. Would make sense. I'd wear the pants and sneakers too if I were him.
Many coaches do. Calipari has a sizeable deal with Nike, but they don't force him to wear a track suit during games.
I have no problem with Lav wearing under Armour sweatshirts around town and to a HS game. If they paid me, I would do the same.
I read a story that in a post game interview Jimbo Fisher of fsu had his arm wrapped around his son on the field, and the son was wearing an under Armour shirt. Nike flipped out, because they are paying fsu and fisher so much to be displayed prominently