Maybe, maybe not. It can also be explained by Apple wanting to do the minimum required. First choice: no PWA support at all, Second choice: PWA support independent of custom browser support, and final choice (most work): PWA support on top of the custom browser support.
The only thing we know for certain is Apple has shown no interest in making the best user experience given the rules vs complying with the rules only where required to.
That said, I doubt it here. they thought a feature was barely used and got enough flack to realize it may get them in deep wanted with DMA. But we don't know how strict they are with PWAs specifically. They probably backed off to prevent anymore of the various issues they caused themselves over this whole thing.
If so, it’s working. Now all the commenters who assume that Apple is doing the worst thing possible at all times are praising the EU for forcing Apple to save PWAs.
Otherwise they’d be complaining about how Apple was intentionally crippling PWA support by not letting you pick the rendering engine used.
The only thing we know for certain is Apple has shown no interest in making the best user experience given the rules vs complying with the rules only where required to.