If he is on the heliroute, that route is chosen because it offers options in the case of catastrophic emergency. A heli can land on a relatively small patch of ground - hence the different application on clarance rules. It may be that though this looked tricky from your viewpoint, it looked very much different from his - and that is the view that counts.
Even off the heliroutes, there are specific rules for twins which are different to singles.
Anyway, with a mode S transponder operating you can rest assured that his exact position and hight was known to ATC. Very, very unlikely that he would break any rules with a very clear record being kept of his every move.