That is right. Allow me to explain it as follows. We cannot be criticized for not having done so because strictly speaking, there is no obligation, under international law, to respect a treaty in a country that has not signed it.
Let's be more concrete. If Canada must deal with a file in Saudi Arabia, which has not signed The Hague Convention, then it is not obliged to fulfil its international obligations. It may wish to do so. Many of my colleagues would argue that this is an erga omnes obligation, that is, that it exists with regard to all of the international community. Concretely, before an international authority, we cannot be criticized for not having respected The Hague Convention in our decisions concerning a given file in a country that has not signed this convention.