One thing to weigh when considering signing is that no matter how vague they make wording, they can not have you waive all your rights simply by consenting. If they could, no organisation would be wasting time and money to comply with GDPR; they would all just change their consent forms to be as vague as possible like this to cover their butts. That would obviously defeat the whole purpose behind the new law, and the fact that we don’t see that indicates to me that no organisations (apart from Watchtower, apparently) believe that they could get away with it.

That is not to say that you should just sign the thing without a thought, but just to ease the concern someone might have that if you are forced to sign, you’ll lose any and all privacy rights you have for good.

(Disclaimer: Just my 2 cents, I’m no expert either.)