I believe SML doesn't have any issue that Robert Harper cares about. It is nearly perfect in all things Robert Harper cares about. Are you suggesting that Robert Harper should care about more things than what he currently cares about?
I disagree with your opinion that he doesn't criticize SML because he was involved in the design. SML is not perfect, but Robert Harper does not criticize SML because SML is Robert-Harper-perfect. Or nearly so.
I disagree with your opinion that he doesn't criticize SML because he was involved in the design. SML is not perfect, but Robert Harper does not criticize SML because SML is Robert-Harper-perfect. Or nearly so.