They claim there’s a technical reason instead of a financial one:

"Snowdrop relies heavily on disk streaming for its open world environments, and we found the Switch 2 cards simply didn’t give the performance we needed at the quality target we were going for. I don’t recall the cost of the cards ever entering the discussion - probably because it was moot.

“I think if we’d designed a game for Switch 2 from the ground up it might have been different. As it was, we’d build a game around the SSDs of the initial target platforms, and then the Switch 2 came along a while later. In this case I think our leadership made the right call.”

No explanation was given as to why they didn’t forgo the key card altogether and just release to the eshop only.