Not a lawyer, but to my knowledge, GDPR does not care if something technically "can be blocked" with some effort. It cares if there was clear, voluntary consent to share a particular bit of data - which wasn't the case here.
Let's say I'm dumb, and I run into the dagger that you're holding. The case is then investigated by the law enforcement. Who do you think they'll blame? Would I be deemed guilty, and would my crime be not having armor on?
> If I hold up a dagger and announce the fact, why would you run into the dagger anyway without protection? Put on some armor, dude.
That's really your position? If people get stabbed, it's their fault, everyone should just put on armor when they leave the house?