I'd be real nix on using oil on spalted maple, since also it would make correction of a problem hard if it doesn't turn out well.
There are commercial "rotten wood" strengtheners... those might be of some use, but it would be nice to test on an area that wont show.
For a home finish, I'd be inclined to get a boatload of water thin CA adhesive and use that to fill and strengthen the wood. You'd do that after staining/toning if wanted the base wood to have a color (ie the middle of a tobacco burst).
StewMac sells a "clear" grain filler that does an "ok" job too, but I've not used it on deep really porous wood like spalt maple can be. I mean, I've seen spalt that is pretty much like coarse cork board. Whaddaya gonna do with that? It needs epoxy or CA flowed into it. Not beyond the home finisher, but neither is it just a wipe and play finish.
There are commercial finishes you can get at places that specialize in marine wood. I've got a place local to me called "Glue Products" that sells all the marine, furniture and custom auto finish materials and supplies. You might seek out such a place and get something similar to the epoxy they use to coat bar tops with (just use it thin of course).
For certain, spalt is a challenging thing to get a finish on.