I don’t see why a maple top wouldn’t work, but I don’t think it would be ideal. It would be prone to damage and depending on the finish, might not be smooth enough to act as a router table surface.
Instead, I’d look at adding bracing to the underside of your existing top. Specifically, you could turn it into a torsion box, but with an opening in the middle for the lift/router. I’d probably use 1/2” or 3/4” ply for the grids, spaced 6 inches or so apart and about 1 1/2” deep, with a sheet on the bottom (with router opening, of course) to tie it all together.
Torsion boxes are easy to make, and are very rigid. I’ve made them from particle board, plywood, MDF, and even OSB, and they all remain very straight and rigid.
