imo, after studying more closely, I would conclude you are correct: TTM should work perfectly. going forward i'm going to include it in my qt processes with a slight change to the TTM.
some fact i found.
-i found no evidence that tomonts are found on fish, as bob fenner suggests, and since they are small and actually don't "dig" as deep as ich it may be more unlikely it encys on the fish.
-"Trophonts remain attached to fish for 2 to 5 days at 24 °C, although
some individuals may detach within 24 hours." SRAC Publication No. 4705
-A. ocellatum isolates from diverse geographic origins and from different species of fish are all the same species (Levy et al., 2007)
-At 20 °C and 20 to 40 ppt salinity, the time between detachment
and emergence of infective dinospores of a Red Sea isolate
was 3 to 6 days (Paperna, 1984a)
with these facts in mind, a simply change to TTM should eliminate ich as well as velvet. typically, when using TTM, transfers on done on days 4, 7, 10, 13; if changing transfer to days 3,5,7,10,13 velvet and ich will be eliminated. also starting the process with a formalin dip to kill all dinospores would be needed, imo.
in my daily life i'm lucky to be able to speak with professionals in fish hatchers, public aquariums, and marine biology. when i ask them about TTM in the QT processes they almost all look at me a little strangely, but after a moment of thought i get, "that could work if you follow the life cycle". Point being most pro's would fine TTM impractical, but for hobbyist it's invaluable.