The technology was doomed from the beginning. Yes it worked but it would cost much more and the efficiency is less than what is currently used and sold into that market. This has been tried many times before and failed the same fate but this time with a new twist . . . . Klystrons.
None has worked beyond the laboratory when scaled up and Frank knew it.
The vision must be followed by the venture. It is not enough to stare up the steps - we must step up the stairs.