And why not charge them with wasting police time as well?

One of the following explanations for this story (also reported here) is true. I have no idea which.

1) David Blunkett (and/or his senior Home Office advisers) have gone stark staring batshit crazy
2) Blunkett is now bored of being part of the Government and is trying to get himself sacked for proposing something incredibly stupid
3) There's a sweepstake amongst members of the Cabinet for who can propose the most ridiculous policy idea and then implement it. Blunkett was probably already winning this, but he wants to make sure and this is the way he's going to do it
4) A large quantity of crack from a recent drug bust has found its way into the water supply at the Home Office
5) Blunkett et al sincerely think that this is a good idea

I'm open to other suggestions, especially those involving replacement by shape-shifting aliens from the planet Draconia, but I really doubt any of them are going to make sense.