Of course it's not stupid.Every sovereign,civilized country has the right (and the duty to its citizens) to exclude aliens from entering that they deem "undesirable" and using criminal convictions as a yardstick to determine undesirability is as good as any way.
I agree with you mate. Funny thing is that its so discrecionary, blocking Martha Stewart but letting in blokes like Tyson...
Im not arguing about a little leeway given to certain people, but the UK should say this, and make it clear its not a blanket ban to one and all with a record, cos its not!