By reading the incident/Accident reports of the CAA website here in the UK you are able to understand why and how some incidents/accident have occurred, however I have never read anything that indicated the loss of control due to pax involuntary input on the yolk.
Control can be affected if the pax leans forward, and if a large pax this can have alarming results, but on the R22 unless you are totally out of your head you hold everything that you should!
PeterR-B
Vfr