Earlier quoted context omitted.
Other than awe for US military capability. What motivates this idea? Not only does it explain nothing, it requires additional explanation.
It's not a complicated or even malicious "coverup". They hear an anomalous sound, but don't know with 100% certainty that it's came from the lost sub. What is the Coast Guard supposed to do, not do anything the past few days and say it's because "Sorry we heard a loud sound at that time and are 99% sure that those people are dead"?
"Coast guard gets report of lost sub and searches for a while".
Why would you turn that into
"USN knows that a sub imploded. Did nothing observable. Coast guard gets report of lost sub and searches for a while."
I looked at the link, I can't see any reason to interject into that more capability than was demonstrated. It may exist, it may not. There is no reason to comment on additional capabilities based on this event.