Parliament was not intended to have the final decision on article 50.
That was the whole point of the referendum.
Everyone knew that Parliament would overwhelmingly oppose its being triggered.

The decision to leave was to be taken or rejected by the people and not Parliament.
All the parties and all politicians and both campaign groups accepted that.
The legal challenge on May's right to act on the decision was brought by private individuals.

The government lawyers say they have a strong case and are confident of winning.
It will be decided on fine points of obscure constitutional law.
It has not been decided yet.

I made a prediction not based on law.
I am in awe of all you so versed in constitutional law that you can pre-empt the judges whose decision it is.