At the time they started development they didn't really know the Switch would be a successful market. By the time they would have had confidence, the game could have not lived up to expectations and maybe they decided more ports didn't make sense. There are also issues with rights that can be very tricky especially with Disney and older games. Might have been that the contracts didn't allow Capcom to put it on any other systems, and Disney wasn't willing to extend it to the Switch at the same cost, or had a general change in policy, etc.
I'm thinking it's something along those lines. The game was in development before the Switch has released. If it had been released in say 2019 then I bet therw would have neen a Switch version as well.