If we follow the logic that the PM can be FORCED to sign a letter that he disagrees with because the parliament demands so. Can’t the people rise up against the parliament and demand that the parliament respect the PM who is doing what the super majority of the citizens are demanding of their Government?
2. "can't the people rise up against parliament.." - of course they can.
"the super majority" -- what super majority? only 37% of the total electorate voted LEAVE. And there is not even a simple majority for No-deal.