Did it dry hard enough to walk on it? Or is it still sticky? Linseed oil has no binder in it normally so there is no reason to expect it to harden.

I would wash it off with NAPHTHA and put a proper finish on it, something like poly varnish. You could use paint thinner but that leaves an oily residue and you would have to wait a while for it to evaporate where NAPHTHA evaporates cleanly. Wear gloves for work with either solvent.

Either solvent will take the linseed oil off the surface but probably not get it out of the pores of the wood, but that is no problem.