It's really quite simple. The Police have an obligation to assemble and submit to the courts ALL relevant information pertaining to a case. They are not being overzealous, just doing their job. Sometimes they have to put up a fight to see how much evidence they can get. It's then up to the courts to decide whether or not it can be admitted, and ultimately (with the assistance of a jury) whether or not liability should rest with the defendant. If they fail to pursue this task, then they are negligent in the performance of their duty, and the victims and their families have cause for complaint.
As a professional pilot, I have a great deal of sympathy for the crew in question, and for the safety argument behind the change to the law. In fact in a previous life as a police lawyer I was consulted and involved in the legal process that brought about that change. However, as a former street copper who on the day of the crash had to inform next of kin face to face, I have more interest than most in determing the truth about what really happened that fateful morning. The deceased and their families deserve that.
Whilst this is an issue about the collection of evidence rather than the limits of liability for negligence, I am constantly surprised at the number of pilots who think that they should be exempt from normal standards of legal responsibility because supposedly aviation is in some way different from other occupations. That is not the case. Flying an aircraft is not an 'exact science' and there is always the risk of unwanted intervention by factors such as weather / bad ATC / other traffic, but this does not reduce the standard of care required of us as professionals. If we stuff up, the law will examine our conduct and we may be held criminally responsible if our actions fall short of its expectations.
It's no secret to say that there was a hint of negligence in this case. Whether or not there was 'sufficient' negligence to result in culpability is yet to be determined. People in other professions as varied as doctors or bus drivers are subject to scrutiny and responsibility for their actions when something goes wrong, even if it was a momentary lapse of concentration or the smallest degree of negligence. If this is the standard that society demands, why should pilots be exempt? Or should we be held to a lower standard of care at work, at least until we leap into our cars to go home and the duty of care of the 'prudent driver' kicks in, ironically when the potential for disaster is much lower?
In any event, I hope that this matter is resolved quickly for the sake of all involved. The only truly inexcusable element of this case is the delay and uncertainty that the pilots, their families, and the relatives of the victims have been subject to. That is an extremely unfortunate consequence of our legal system.
I wish everyone involved, the best of luck!