Dude...no reason to be yelling. You are the one that said you were a citizen, not me. I'm well aware of the fact that I can't just move to Canada as a US citizen - why else would I have all those little notes and dates under my profile if I thought otherwise. ;D
My point was that while you are indeed traveling to Canada and you do have a green card, you are not a U.S. citizen. Because this is for your COPR, they are doing the passport request based on your country of citizenship, which is Cuba and is not visa-exempt. I don't know what's customary for Cubans coming as permanent residents in terms of the passport requests (original vs. copy), and admittedly missed the part about original that you mentioned, so you may well have a point there. I'm betting though that for the other green card holders you mentioned who were asked for copies rather than originals, it was based on the country their passport was from and what is customary for that country, and not the fact that they were green card holders.
As someone else pointed out, your passport is still from the country you are a citizen of, and in the end that's what matters for your COPR.