I'm certainly very interested in hearing the clerk's and the chair's reasoning on this, but we are talking about an accountability act, and this goes to the heart of our electoral and therefore our democratic process in that it speaks to the will of the electors of a particular riding to have the right to choose their member.
I can't think of anything more fundamental to the accountability of a government or members of Parliament than keeping faith with the electorate. I do point out that what it gives the member who has left the party to join another party is a fair opportunity for that member to go back before his own constituents and make his case. Perhaps if there was some good reason why he left the party and joined another one, he could make that case to the electorate.