I no longer understand what argument you are making, if I am honest. The referendum result was "advisory" in the sense that it was non-binding in law. This is fact, plain and simple. The Act in 2015 to allow the referendum was merely about allowing the referendum, not allowing the result. This is also fact. And therefore, since implementing the decision has consequences on the rights of British citizens that were enshrined in an Act of Parliament, only Parliament can vote (in a separate piece of legislation) to overturn those rights. This is what the judgement says. May is appealing it out of bloody-mindedness, nothing more.
What, exactly, are you arguing? That the judgement was wrong? No, you've said you accept it -- albeit with the caveat that the government's position may not have been presented well, and it is true that we will have to see what the Supreme Court returns. That the referendum result should still be accepted when Parliament votes on it? If so, I am not intending to argue against that either. That the Referendum Act provides the only vote needed by Parliament? But we have seen that this is bogus, both because the judgement confirms this and because the government, in reality, accepts it.
If it's simply frustration at the case being brought in the first place, that rage had better be directed against David Cameron, whose fault it really is that we are in this mess.