I think it reasonable to say anyone with the clearance and the need to know had been informed of the Navy's suspicions.
Until the Titan was found, all the sounds would be conjecture, much like the banging noise.
Imagine the outrage and conspiracy theories if they called off the search based solely on SOSUS analysis.
They had to search.
Military spokesman said the implosion detected was just lines on a graph, not definitive, and in no way would convince family members or other members of the public to call off a search. He said that was standard procedure in these types of accidents, they detected an implosion of a cargo ship several years ago, but still went searching, 33 men died, don't think there were any survivors.
I think waivers are generally effective, very much disagree with the premise they can be easily tossed out in court, especially when the danger is so obvious like on the Titan.
BUT . . . one way to overcome waivers is to show they were procured by fraud. OceanGate website said the Titan was designed with help from Univ of Washington and Boeing, and co designed and manufactured by the NASA headquarters in Huntsville, AL.
That statement was deleted from the website in the last few days after UW and Boeing both released statements saying they had nothing to do with the Titan, and NASA said they offered some general advice to OceanGate about what type of materials they might want to use to construct the vessel, but absolutely did not design and/or build the vessel.
Those type of misleading and false statements will get any document signed in reliance on those statements invalidated.
Of course, getting a large judgment may be the easy part, collecting from a BR entity with no insurance is going to be a tad more difficult.