You seem to be coming round to my way of thinking...
Except... I think if he has a photo it's clearly MM
I think there does exist a link but not strong enough for court.
He may well have more circumstantial and has asked people for descriptions of the interior of places CB has frequented which would support the existence of a photo
I think SY are totally on board and the missing person statement is Semantics
Even a tenuous link would probably be sufficient for them to grill him. Yes, I know they'd be playing their hand, but I'm sure CB and his legal team can join the dots just as we have, so that reason for not arresting doesn't wash with me.
These photos cannot be definitive. They may be definitive in terms of an ID of MM, although I doubt that, but there's no way to put CB in the scene.
I'm no crime expert, or indeed expert in anything (using the Gladwell '10,000 hours' definition), but if there are photos and there's a suspect but no link, this must be unique when the circumstances are factored in.
At some point in this drawn out circus HCW will have to give it up. This link will only ever come from CB himself; that much is now clear, a year on from the initial proclamation.
It's the essence of Catch 22 as Heller described it - there's not enough evidence to arrest CB according to the prosecutor, so they can't interview him. But even if they interview him and show their hand, now that he is pretty certain that they don't have enough to charge him, he just has to sit there and say nothing. So HCW knows this is how it plays out, so he has to keep looking for this corroboration that he has failed to find in at least a year (potentially 3).