What would be called into question would be the relevance of that school's / any schools 'grading' -- at very least it would indicate that the grades neither predicted.. (nor could they have measured)
-- the quality of mind now evidenced with every complete-sentence since the one which first got him Noticed as
-??- (exuding Sanity in a milieu where doubletalk and slogans predominate to the point of being mostly, trite politico-doggerel.)
IIRC Einstein also did poorly in the Grade game.
qed