I have had an update from the Canadian Yachting Association on this topic. Apparently this was a very old rule that has been out of use for some years. See below for their response.
"RRS 50.2 covers the use of whisker poles. The only restrictions are
shown i.e. one pole and when in use it must be attached to the mast.
There is no restriction about what side of the mast the pole must lie.
There used to be a restriction (RRS 1989-1992, rule 64.2) that a
spinnaker pole or whisker pole must be attached to the opposite side of
the mast to where the main boom was carried but this rule was changed
many years ago when the 1993-1996 rules were adopted."
Thanks for all the help,
Mike