Powered coating is done using heat to melt, settle and cure the paint.
Flow formed wheels are made from cast wheels having the rim heated and rolled to a much thinner thickness to lower the weight and make them strong enough to be made much lighter than a regular cast wheel, it can be thought of a type of rolled forging.
Powder coating a regular cast wheel is not likely to be an issue, doing it to a heat heat treated cast wheel like the TD's or a flow formed wheels could lead to a catastrophic failure is not something I would take a chance on.
Painting and air drying or low heat curing is how I would deal with forged, heat treated or flow formed wheels as I have never seen wheels like these power coated by the manfacturer. (some may do so but it would be parted of the process of making the wheels stronger, not done after already heat treated, etc)
I am not going to look for threads to list here as have seen dozens if not hundreds of posts about this issue over decades of modding cars and have seen pictures of failed powder coated wheels, it is out there.
Will it cause a failure of the wheels in this thread? I do not know, I would not take the chance personally nor take the word of "Joe's Powder Coating Shop".
Rick