In light of some of the comments in this thread about this unfortunate man's possible exposure to criminal prosecution I undertook some research. I should make it plain that my experience is in a non-UK - but nonetheless common law - jurisdiction (Australia). Before anyone starts flaming, I practice in criminal law, not personal injury, and have a lot of experience on both sides.
Unlike where I practice, there does not seem to be an offence of "dangerous operation of an aircraft" in the UK. Here, this offence lumps aircraft in with motor vehicles, and does not require any reckless or negligent behaviour. Rather, all that is required is a state of affairs that is - viewed objectively - dangerous. Momentary innatention may amount to dangerous operation, but there has to be flying that is far below what would be expected of a competent, careful pilot. I can only recall one aviation conviction for this offence in the last 30 years, and it involved an ultralight pilot buzzing his estranged wife's home.
I may be wrong, but I did not find any UK equivalent that applies to aircraft - only motor vehicles (ie Road Traffic Act 1988 (UK)).
There used to be an offence of dangerous flying in section 81 of the Civil Aviation Act 1982 (UK), but that provision was repealed. I haven't found a replacement for it other than in the Air Navigation Order (UK), which contains a prohibition against reckless or negligent flying that causes or permits danger to any person or property. An offence against that provision would require proof of recklessness or negligence.
Then there is manslaughter. The test for the offence of manslaughter by way of criminal negligence is high, and is the same here as it is in the UK - what is required is recklessness involving grave moral guilt, ie something that goes beyond the mere payment of compensation for personal injury/loss and which shows such disregard for the lives and safety of others as to amount to a crime against the state and be deserving of punishment.
Proving criminal negligence or recklessness beyond reasonable doubt is often difficult. Offences such as "dangerous operation of a motor vehicle" were introduced because juries were notoriously reluctant to convict in vehicular manslaughter cases.
Further, anyone reading the AAIB report should bear in mind that not all of the evidence identified in it may be admissible in a criminal court - particularly things said by the pilot to investigators.
Having said all that, there will inevitably be an inquest. Experience shows that Coroners may not uncritically accept the conclusions of accident investigators.