A valid question would be:
" What does this court ruling actually prove.... about the USA, about Canada, about illegal aliens?"
It's not about illegal aliens, it's about refugee claimants.
It's about the internationally recognized concept that someone can flee thir country, and as soon as they reach a safe country, they can apply for refugee status in a 3rd country. The safe country concept allows a refugee claimant to stay in the first safe country they reach. The US has said they would detain and possibly deport such claimants.