I haven't paid a lot of attention to Stoller particularly, but the rest of that line of thinking frequently correlates with also believing that monopolies are exclusively a result of active government regulation, a belief which is naturally attracted to Republican deregulatory rhetoric.
Oh, I don't think that applies. He's part of a movement called "neo-Brandesian" aka "hipster antitrust", which basically thinks government should promote small businesses by explicitly bullying large businesses, and that the customer welfare standard was a cop out to give up on this.
So not only would they be against deregulation (they think painful regulations are good because pain for the sake of it is good), but the previous admin actually tried this with Lina Khan and it didn't really work.
The issue here is Democrats are "mainstream" coded, so all populist politics works by fighting them even when they're trying to do your own policy.
