I think the minister also made this point when he was here earlier. What the escape clause does is create a situation whereby MMPs currently in the statute book that have been struck down by the Supreme Court of Canada or held to be inapplicable by other courts at other levels are reanimated.
They apply again, but this provides a small window of judicial discretion to allow judges to depart from a mandatory sentence in situations where they may otherwise have to strike it down or not apply it in a particular case because it would offend section 12 of the charter, the right to be free from “cruel and unusual treatment or punishment”. In that respect, it reanimates MMPs that are not currently at issue while allowing for judicial discretion.
I would also like to clarify that the exception for the MMP doesn't impact a judge's ability otherwise to impose a just and appropriate sentence.