They would be missing out on so much money otherwise
Would they? The 360 is barely alive in Japan and I doubt the Western Persona fanbase who only own a 360 would make much of a difference to Atlus.
Even if I thought that last statement held any merit, look at it this way:
The game is obviously being built on a variant of the engine used for Catherine. The port work is done. It would be worth the money to do it for a major game in their franchise.