Bellei is neither Direct on point nor a precedent
I hear what you are saying, and disagree. So, at least the issue is unsettled, as a matter of law.
It is factually on point in the sense that Bellei (like Cruz) was born abroad to a citizen mother and alien father, and was a citizen at birth via the same statute.
It is legally on point insofar as the case presented the question of the nature of Bellei's citizenship, concluding that he did not meet the "Constitutional definition" of citizenship and that he was naturalized (by statute) but "out" of the United States. The case is further significant in that all of the dissenting justices agreed Bellei was naturalized (though the dissenters would conclude he was naturalized "in" the U.S. and thus his citizenship was Constitutionally protected).
Under principles of stare decisis what is normally binding on lower courts is not just the decision in the case, but also the core reasoning underpinning the decision (the ratio decidendi). The reasoning that Bellei was a naturalized citizen is central to the decision.
Any case on the merits of Cruz's candidacy would need either to ignore the case (and the recent "scholarly" articles have largely done a fine job of that) or disavow its reasoning and characterization of Bellei's citizenship as "naturalized." Given the courts have signaled they really, really don't want to be in the business of deciding Presidential elections, this is likely an academic exercise. But I don't think passing the case off as inapt is sound.