Unstabilized maple has been used for centuries in furniture, gunstocks, musical instruments, knife handles, etc. Many very old examples still survive quite well, not just in museums but in people's homes, studios and workshops.
Maple is quite stable but not terribly hard or tough, so it shouldn't be used to bash on things or for long hammer/tomahawk handles. (hickory is the go-to for that, again it doesn't need stabilizing, just reasonable care.) As a knife handle, the user will have to keep maple reasonably clean, oil it occasionally, and not use it a club. It will likely outlast him by far.
Undyed, stabilized maple is of course denser and more resistant to the elements, and makes a very nice, low maintenance handle. Dying it is a matter of taste.