Parliament treats Boris just like the Dems treat President Trump.
Agreed. But the question remains. Does the PM in his capacity of the EU member have the authority to vote no / veto the request contained in his own unsigned letter? I would say yes.
The British media, Labour party, and Tory remainers have been calling him "The British Donald Trump", along with accusing him of breaking the law, and acting like a dictator ... it's just part of a Globalist's DNA.