I entirely concur with the ICAO definition, and it was not helpful that the SQ crew were arrested while the investigation was still under way.
HOWEVER, it should perhaps be noted that there is nothing in any Ops Manual, International Treaty or National Statute that gives flight crew invulnerability from prosecution in cases of gross or ciminal negligence.
And note the definitions (generally accepted). A mistake is one thing. Negligence is another.
It is beneficial if an accident investigation highlights how a crew were led to making a mistake - to highlight the Human Factors, the Environmental Capture etc.
But if an accident is, quite simply, the result of gross negligence on the part of the crew, then is there any reason why they shold not be subject to the response of the law?