CW
As to "Why Now?", I think for a couple of reason that there has been a fatality that even though drugs weren't attributable as causal in the accident, it demonstrate that they did exist in the pilot's system at the time of the accident. Even though in this case you couldn't say that it demonstrated a representative level of usage in the pilot community it does reinforce what others believe that the level of usage in the aviation community could be a concern. After all the level of usage has increased across the community and there is no evidence to suggest that that increase hasn't also occurred in the aviation community.
As an aside, in recent years there has been an increasing tendancy to cite organisation (management) failures that contribute accidents.i.e bad decisions in resourcing, funding etc. that have contributed to an accident. Will these managers also be tested to see if they are under the influence of drugs and alcohol when they make decisions?(from some of the decisions I have seen, you would think so!)
Lets hope they come under the spotlight as well. Presumably if they hold an ASIC they will. On the other hand they might just tend to stay away from airside more.