There are really two separate, potential uses for provisional ballots going on here, then. One is, as you mentioned, in the case of Mr. Opitz's election, where a number of ballots couldn't be validated. Had the provisional balloting been in effect, I gather you're saying that although the vote count would not have been very fast for those ballots, we could in each case have guaranteed that either (a) it was a valid ballot or (b) it was not, leaving no lack of certainty.
On May 12th, 2015. See this statement in context.