Veeeeery interesting! I do believe you’ve named the smart-money option on why Zer0 won’t release his grades. (Although sheer arrogance is still a possibility, of course.)
Or his LSAT's (and SAT's). The release of LSAT's more consistent with a mid-level law school than with HLS Magna would be devastating. Obama's only life achievements are being named President of HLR, and making Magna at HLS. A 60'ish percentile LSAT would show these HLS honors to be contrived, and his resume to be fraudulent. If this is shown to be a fraud, then the question is what else? It calls the autobiographies into further question, etc. Pull on that string, and the whole thing collapses.