FosterBoxerMom,
I suppose I am trying to work out what the DM/DG was seeing and how he may have been under the wrong impression of what the status was of the divers in the group was. I have been in a situation where, for whatever reason, buddy pairs were switched during the dive or a buddy pair became a threesome due to someone surfacing early, it happens from time to time and I suppose this is not always covered in buddy checks/briefing.
At some point maybe he sees your hubby ascending towards you and makes a connection that Brendan (mis-ident) is joining you, he looks again later and sees that you are now only 2 again and queries you as to your buddy (thinking Brendan) and you give an OK signal, perhaps he is now thinking that Brendan has surfaced and you are showing him that all is OK.
This is all speculation, I am just trying to see it through the DM/DG's eyes and how he may have mis-interpreted events. (This has no bearing on site selection or briefing, I get that.)
Based on you saying that when the penny dropped on the safety line (safety stop?) and he realised you were missing someone, he "shot" to the surface, I have to assume that if he had actually realised and understood that there was a problem (missing customer) during the dive he would have reacted differently than just continuing the dive.
Best Regards
Richard