The definition of a public office-holder is not the clearest in the world, and some areas could be improved by some amendments. With the example you gave of the people who were asked to voluntarily comply, the wording of the act refers to people appointed by the Governor in Council. These people were not appointed by the Governor in Council; they were appointed by somebody else and approved by the Governor in Council, so technically they were not caught by the act.
My sense is that with an act, particularly when it's an onerous thing, you have to apply the strict wording and not go beyond that.
There weren't very many of those people, incidentally. There may have been between five and ten.