I would argue that you should exhaust all carrots before you move to sticks.
I don't think it benefits us to take a system where people find their voice isn't included and then force them to vote. Number one, I don't think we should talk about mandatory voting. Mandatory attendance, the fact that you would have to show up at a poll and take a ballot, that I'm a little more open to. I haven't voted in past elections for some of the reasons Mr. Cullen was talking about. A “none of the above” option wouldn't have satisfied my concerns. I wouldn't have wanted to cast a ballot. That would be an issue of free speech for me, really.
I'm not, on spec, against mandatory attendance, and I don't think Denis is either. But I don't think trying to legitimize an archaic system of power works the same way. You should use that when there are other alternatives available.