It looks like the COSPAS-SARSAT rules are not made for this kind of situation - where the ELT may be shortly submerged or destroyed but there is a very large interest in locating the wreckage, survivable or not. I guess they value avoiding false alarms over occasional missed finds, but one would hope there would be a better way of signalling that an activation was false, so the 406 data burst could go out ASAP.
It has been my experience that non-survivable small aircraft accidents usually destroy the ELT or sever the antenna or antenna connection, but this is a different situation. It has also been my experience that ELT's go off way, way too often when there is no emergency, but again, different issue.