I was baptized in 1986, so I took the new "oath."
As for the legality of it, please notice that your oath involves you 'understanding' that the JWs are "God's spirit-directed organization." Tell me... which court would recognize that? Or how would you convince the court that the WTS is in fact God's spirit-directed organization?
That's not going to happen. This is not a legally-enforceable contract. The wording was changed because the GB wanted to insert itself between the individual and God, which is what they have been trying to do for decades. They're not claiming a contractual authority, they are claiming a divine one. No court would accept that claim as part of any litigation.