Sure.
First of all, it does have to be shown whether Minister Morneau knew, or thought for sure, that he had paid for all of the costs. So that investigation needs to be done. To prove breach of trust, four of the five elements are already proven; he's an official, and so is the Prime Minister, taking part in a decision, in an official decision-making process, and breaching the standards of office in a serious way. The fifth one is whether it was done intentionally. That's where the investigation needs to look at the whole communication record.
But when you have that relationship with the charity, and you have been found guilty of violating the act before, as the Prime Minister and finance minister both have, and you're still taking part in directing your staff to take part in the decision-making, knowing that it's wrong, then I think that is evidence of wrongful and dishonest intent.