I first want to say that my answer will be limited to my area of expertise, which is constitutional law. That means I can't answer your question directly, except to say this.
I'm going to cite an excerpt from the Supreme Court of the United Kingdom's decision because it's important to understand the two types of explanations that the government can provide.
It says, “The next question is whether there is a reasonable justification for taking action which had such an extreme effect”. Here they were talking about proroguing just before Brexit so that Parliament could not negotiate and discuss and deliberate things. The court goes on, saying, “Of course, the Government must be accorded a great deal of latitude in making decisions of this nature. We are not concerned with the Prime Minister's motive in doing what he did. We are concerned with whether there was a reason for him to do it.”
The court makes a distinction when it comes to a subjective reason. My colleague Mr. Brodie said that prorogation was strictly a political decision, one made for political reasons.
From a constitutional law standpoint, however, was there a reason to prorogue? That's what the government provided in its report. It's up to parliamentarians to determine whether the justification is sufficient.