I believe there was a similar move by the widow/partner of the pax in the Mick Goss/Harding accident. Not sure what the outcome was: does anyone know? [I am not suggesting there is any similarity between the circumstances of the accidents, but the legal relationships are not radically different].
For civil cases, such as these, the test is one of the balance of probabilities, so it is much easier to argue the case as a plaintiff than as a prosecutor. Some might think that, if you have the funds, it is therefore "worth a punt".
Talking generally, as I have no particular knowledge of this case, (other than knowing AJ a little), it seems to be the modern way is for the bereaved to desire to blame someone through the courts. The only certain winners in such a case will be the lawyers, of course.
It is a cautionary tale for all of us who operate freelance/self-employed or indeed through our own service company. Who wants to have their family facing such a legal case, after their death, presumably with the prospect of losing the family home? However, what do you do to prevent or mitigate it, other than be careful and cautious (as SASless suggests)? I am distinctly less "bold" than I used to be, these days. Expect support from no one.
I raised this issue of the freelancers' liability in a thread a while back. One key practical step suggested was to try and get you, as an individual, named on the aircraft insurance. This may be easier in some cases than others.