The PC can, and should, do absolutely nothing. The matter is between the complainant and the MO if it is submitted to MO.
If the individual was acting in a private capacity, then the MO has no jurisdiction.
Only if the individual was acting, or holding them self out to be acting, in an official PC capacity would the behaviour be anyone’s business other than there own
Private activity undertaken by a private individual (even if a parish councillor) is private business - unless it is criminal then it might be police business but even if it is police business, it does not automatically become PC / MO business