What the Supreme Court has said here is that they don't like or believe the justification. But who are they to decide that? There's no law or legal precedent here for a court simply deciding they don't like a justification for a prorogation. Constitutional tradition says it's actually the Queen's decision, which she makes based on advice from the Prime Minister. The very new Supreme Court has nothing to do with it.
At any rate, regardless of (pointless) arguments about a non-existent constitution, the realpolitik of this is that the UK is heading straight for civil war.
Parliament refuses to let the UK leave the EU by its own deadlines, an outcome it had itself voted for.
It refuses to trigger a general election.
The Speaker has given up the traditional role of political neutrality.
Many MPs have not only announced they will fight against the very policies they promised during the last election, but actually quit their parties and joined parties with opposing policies, whilst refusing to trigger a by-election so they can be judged.
One major political party is now openly saying if they get enough power, they will simply cancel Brexit entirely. Labour is not far behind.
At all levels British democracy is in outright collapse. This is not due to actions of Leave supporters or campaigners, but rather due to coordinated efforts by people who are ideologically committed to the EU and who are willing to destroy any institution, tradition or constitutional procedure whatsoever in their efforts to do so.
How can people respect their government when they see politicians so openly doing U-turns on their own position the moment they won an election, when they see those same politicians refusing to allow new votes except for those they've rigged so leaving can never win?
At some point the UK is going to cross into seriously extreme territory. If voting doesn't work to change those in power - and right now it clearly doesn't - then what's left but violence?