I don't know who exactly made the decision to let the case get this far, but it's worth noting the judge explicitly credits crown counsel with suggesting an acquittal:

> [7] After Mr. Epstein testified in chief, in a tremendous display of professionalism and objectivity, Crown counsel declined to cross-examine him since, in her view, it was not in the public interest to do so. Instead, she humbly invited the Court to enter an acquittal. Having heard the evidence, I can unreservedly confirm that she made the right call. Counsel’s integrity was commendable.

One thing that I found in reading the judgement was that French/English tensions came into play (the accused was Anglophone, the complainant had taken exception to him speaking English) which is a political hot topic in Quebec right now. It's possible there were some political motivations in play.