Just because a manoeuvre is out of the ordinary, not in your own experience or not in your own skill set doesn't make it dangerous. It may or may not have been illegal depending upon how one construes 'normal aviation practice' when quoting the 500ft Rule Exemption for Take-off and Landing.
As a Helicopter Examiner I see all manner of manoeuvres that are 'out of the ordinary'. Depending upon the ability, experience and awareness of the Examinee reflects upon whether I consider a manoeuvre acceptable or safe.
I suggest a further quiet chat with the individual might clear things up without unwelcome intervention from the 'Feds'.
JJ