TBH,
I’ve no problems with filling it in. I did it online, took no time, and I don’t need a tinfoil hat to protect me from Them.
However, if some cleverbollocks comes knocking on my door, wasting my time, to chase up a form that I’ve already filled in, I’m likely to have sense of humour failure.
It’s not hard to cross-reference “addresses” with “forms completed” for a start, so we’re looking at harassment and possibly trespass(?), but moreover I don’t think it’s a particularly smart idea to be going door-to-door reassuring people that it’s ok to give out personal information to people who come knocking on the door asking for it.