A very nice additional idea, Masem. I wouldn't change the copyright statement in any way, though. Just pick a random character from it, it is an English sentence at the moment so it already matches the distribution of letters (or at least as roughly as anything else) and the main point is just to get a random letter ... I don't think it's a problem if you never get an x.
Although the '&' might look a bit strange as a letter. And I don't think you can get that out of the copyright ;-)
Update: Added the '&' remark.