On mine (which has the shower), I can see the wax ring by looking up from underneath into the hole. I think (but would not swear) that the wax ring is installed to insure that water in the shower pan goes out the drain and not down the hole. If the wax ring deteriorates (or should I say when it does), then I think that shower water will run out the hole. If you seal the hole so water cannot drain, then, when the wax ring fails, the water will sit in the black water drain hole in the floor and the wood will rot. The wax ring is under the black water tank so you cannot inspect it from inside. Leaking water would be your clue that it had gone bad.
Now if you don't have a shower then ignore what I just said.
If you are only talking about sealing the cut edge in the hole and not the entire hole, then ditto.
If you used to have a wax ring then perhaps replacing it would be the best option, but it entails removal of the commode and tank, and cutting the black water drain, then replacing it all while using new drain pipe.
If I am wrong about any of this I hope someone more experienced with Scamp
construction will correct me.