No. It is entirely unsubstantiated, and not credible on its surface. Its origins are pretty unclear (one can speculate, but we don't really know where Trohan came up with the idea), but it became part of what is basically a pro-MacArthur, anti-Truman, anti-Roosevelt conspiracy theory — one that only had traction with far-right figures (including some who would dip into Holocaust denial) during the Cold War. Very weirdly, it has been uncritically repeated by scholars today of a "progressive" bent who try to use it as part of an argument against the use of the atomic bomb. But it is entirely unsubstantiated. Trohan was vehemently anti-Truman and pro-MacArthur, for whatever it is worth. No one has turned up any evidence for this outside of his own claims.

For more information — I happened to go deep down this rabbit hole a few months ago.