It's tricky because dissenting doesn't necessarily mean you'd reach the opposite conclusion in every respect.
In this case, I really doubt even the most conservative justices believe "birthright citizenship means whatever an Executive Order says it does." At a minimum, we know they aren't signing on to the reasoning the 5 in the majority used. And then we can learn whatever they feel like saying in the dissent, but a dissent is just an essay with no force of law.