Yes, that's correct. The first part is the restrictions on the topics that he can advertise on with respect to advertising messages to inform electors about the exercise of their democratic rights, and the “for greater certainty” clause allows him to advertise for any other purposes in his mandate. For instance, just as one example, if he's holding a competition to fill a returning officer position, then he would be allowed to advertise for the purposes of that competition.
On April 29th, 2014. See this statement in context.