The Gallagher debacle did not go like you're claiming. Some of the SEALs who reported him went on to choice assignments that I know of personally, and I believe at least one of them has made Chief since (for the non-Navy that's the biggest promotion an enlisted Sailor can get). There's always some measure of risk I suppose, but NSW handled that case by the book. The lawyers fucked it up, and then his lawyer managed to get the case into the public eye and by extension a CINC with no military experience or understanding who interfered in the case over and over.
The military isn't perfect in this area by any means, but in my experience if they're going to err, they're going to err on the side of a full investigation and throwing the military member under the bus whether deserved or not.