Mr. Christopherson, I'd like to add one thing, if I may.
I don't think leaders who fail to show up to a debate pay a democratic price or other penalty in voters' minds. People don't even remember that, in the 2015 election, one of the two major party leaders did not participate in the English-language debate.
That is why I believe some sort of sanction is necessary, if only to force a leader to show up to a leaders' debate. Two or three days later, Canadians have already forgotten about it.