Anything at all can be argued as the product of an Intelligent Designer, even if it doesn't look intelligently designed. "After all, who are YOU to question?" Happens all the time on these threads.
The exceptions to Ontogeny recapitulating phylogeny are so numerous as to point to a common designer as the most logical explanation.
Unfalsifiable does not equate to "most logical." As for exceptions: stricly speaking, you were never a fish. But you were a unicellular, then a simple colonial multicellular, then a primitive chordate, then a fairly simple vertebrate, etc. And although you weren't a fish, you once had pharyngeal clefts that looked like gill slits.
For example, claiming this study is evidence for the evolution of feathers from scales. Hey, maybe they did, but how does this experiment support the idea????
It points out a more detailed genetic scenario than previously existed.
Nonsense. No one argues that the shape of clouds is intelligently designed. No one argues that simple things could not have arisen by chance. The argument of intelligent design is that some things are too complex to have arisen by chance. In fact it rests on Darwin himself:
"If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. "
This is one of the few statements he made proposing how evolution could be falsifiable. Therefore it is perfectly legitimate to take him and his theory up on it.
But in humans they are not gill slits, and have nothing to do with gills, or even lungs or respiration at all. They become parts of the human face unconnected to respiration.
We have gone over this before. These similarities are superficial and in no way indicate that human beings ever have anything like gills at any stage of embryonic development.
It points out a more detailed genetic scenario than previously existed.
Yes it gives us details about what genes are responsible for expression of their corresponding feather parts, but that is not proof of feather evolution from scales. They took a creature that already had feathers, and mutated its genes so that it produced mutated feathers (not even scales, so not only did they not make a lizard go through the mutations needed for scales, but they did not even 'backwards engineer' a feather to scales)- er, even if they did, that last would constitue a reduction in complexity that was already present.