It shows that to whatever extent an experimenter can behave nondeterministically, so can an elementary particle. So it's useful as a simple way to convince people that quantum mechanical randomness is a true fundamental phenomenon (in particular, that hidden variable theories are all inherently invalid).
I've never seen a coherent definition of "free will", but I don't see how someone whose decision is random has any more or less of it than someone whose decision is nonrandom, so IMO it doesn't really have anything to do with free will one way or another.
I've never seen a coherent definition of "free will", but I don't see how someone whose decision is random has any more or less of it than someone whose decision is nonrandom, so IMO it doesn't really have anything to do with free will one way or another.