Not sure about the second part. Considering they have a dominant market position/gatekeeper/whatever, they probably have to actually make an argument for "why not" in the case of tracking blockers (age restricted content is another discussion entirely).
Otherwise, abusing dominance in the phone app store market to benefit their (also dominant) ad surveillance business sounds very, very much like something the DMA could and should punish.
If Google had their own porn app in the Chrome or Play stores, but banned all other porn apps, I guarantee they'd lose quite a few anti-trust related lawsuits, and quickly.
