Gay and Powell both ran a good number of 60s in their break out years (2006 and 2004 respectively) where Powell ran at the WIC (didn’t make the final) and some races in the US and Europe. In 2006, Gay ran a number of domestic races and competed @ the US nationals, but failed to qualify for WIC.
Powell, in many of his best years, also ran a bunch of 100s outdoors in Australia around the time of indoors (including competing in and winning CWG), so the effect would be similar. Both Powell and Gay have had injuries and off-season surgeries in some of the past few years, making early competitions less likely. The year he did that was also arguably his best season from the standpoint he was undefeated, healthy, and ran multiple 9.7s.
I don’t think it is nearly as complicated as people try to imply. Some do it for reasons we can discuss on this board (having to travel, little to no $$ relative to outdoors for those 3 guys only, competing through September and needing some rest) and some reasons we cannot. Considering that at least two of them have run 60s in an attempt to compete well @ WIC, while still with their current coaches, I doubt most could simply write it off as being because they do “long-to-short.”