This not only goes against the Constitution, but is in fact illegal

opinion not fact!

The bill of rights clearly states: Debates or proceedings in Parliament ought not to be impeached or questioned in any court or place out of Parliament'

I fail to see how the court action can possibly succeed. The judiciary are playing with fire.

"the key issue is about “justiciability”, or whether the prime minister’s use of the royal prerogative should be subject to legal scrutiny. The Judicial Power Project at the thinktank Policy Exchange has argued that judges are usurping parliament’s powers through excessive “judicial activism”

This constant recourse to law in recent times cuts both ways of course.?
Can a law be passed when the Queen's consent was not granted?
Can a rabble pass laws in Parliament when they have no accountability.
This latter point is further strengthened by the argument that twice the rebels were offered an election to give legitimacy for their decisions. Twice they refused. In essence the majority of MPs constitute a rogue parliament in opposition to the will of the people.

The inescapable conclusion is that the rebels are very happy to thwart the minority government wish for an election because they know full well, that should an election take place, they would end up with no mandate from the people.