Briefly, denunciation is but one of the principles of sentencing. The problem with bills like this and with mandatory sentences is that they put too much weight on that principle, and in an unconstitutional way.
There's a fallacy in the logic that was employed in the question. These people are in longer so they get more treatment. Well, not if it's six months, not if they're in Alberta; they don't. When we say that this deters, that's what's being said here today, but that's not the bill of goods that's being sold by the politicians, is it?
The justice minister was in here, saying minimum sentences protect. If you want to go out and sell it that we're going to retributive, we're going to deter, that's fine. Bill it as that. If it falls as unconstitutional, that's fine. Your words are on record.
But when you go and sell it as a protection, that's not backed up by evidence. That might sound good when you say it, but evidence is what counts in court. That's why these things get struck down all the time. That's why these ones probably will, too.