Jim, the return of direct rule has nothing to do with Brexit and everything to do with Sinn Fein.
Belfast telegraph last week,
"The DUP and Sinn Fein have been engaged in talks to restore devolution to Northern Ireland since the republican party pulled down the institutions in January. "
https://www.belfasttelegraph.co.uk/news/politics/further-moves-to-direct-rule-inevitable-says-dups-foster-ahead-of-pm-meeting-36

I knocked down all your points but you only challenge this one?
Given up on the others?