Read on...................
How would he prove what? Was there anyone else in the aircraft at the time of the accident? The operation would still be Part 91.
IRISH AVIATION AUTHORITY (RULES OF THE AIR) ORDER, 2004
3. Minimum heights
(5) Nothing in this Rule shall prohibit an aircraft from:
(a) (i) taking-off, landing or practising approaches to landing,
in accordance with normal aviation practice at an aerodrome or heliport within the State, or at an aerodrome or heliport in any other state, and without causing undue hazard to persons or property.
The interpretation of "undue hazard" or unnecessary risk would be the issue.