Read that carefully. He has no idea what happened, but tries to interpret it in a way that makes Apple look good. Typical Gruber.But I think what happened is that when the EC realized the DMA was going to result in a worse PWA experience, they let Apple know that WebKit-only PWAs would not be penalized.
Here is my interpretation. Apple does not want competing browser engines to be able to make homescreen icons, because they migh actually provide a better experience for users than Safari or even the app store. I'm certain, that this is exactly what is going to happen, because the EU/DMA mandates it.
Removing homescreen icons was a knee-jerk reaction that made them look excpetionally bad. It's exactly what a monopolist would do. Make the user experience worse to further their economic interests.
If Gruber is right, there will be no home scree icons and PWAs with third party browser engines. If we will get them, than Grubers article was BS.