It would only be embarrassing because it's dragged on for so long. If we are discussing the same event, it happened what, 2 years ago, long before RN was TD, therefore even the most casual observer would assume it was even brought up for purely political reasons. Then, how long does it really take to investigate this? "Rob, What happened?" "Complainant, What happened?" "Witness, what did you see?". If the witness corroborates the accused story, it's over. If the witness corroborates the complainants story, it's over. If there is no witness, it becomes a "He said - She said" and with a letter in a file somewhere that none of us ever hear about, it's over. If Rob wants to bring it up himself later (Like Jim Wyatt did), he is welcome to do so. I think an investigation like that should take.... oh, maybe 20 minutes. This is damaging to NACD because it's dragged on for over a week.
Are you SURE Rob is accused of teaching Trimix to intro to cave divers? Would you bet a thousand bucks that it isn't something else?