Edit: Sorry for taking so long to respond.
...cruising Safari's menu items reveals that every command that incorporates ⇧ also includes a letter that's displayed as u.c. despite the fact that the command's intention is l.c.
Have you ever seen a menu command that includes a letter which is
not displayed as upper case?
By implication, yes, on my OS X Install and Apple Hardware Test discs where it says
"hold down the C or D key", respectively, and in several similarly worded Apple docs. (Somebody at Apple apparently recognizes that "X" is ambiguous in the context of a keyboard command.)
And in response to Ira, that ambiguity could just as easily lead people to depress the shift key when it's unnecessary, or, possibly worse, when it will produce unwanted results.
And further muddying Apple's consistency is the fact that control and option are represented by ^ and ⌥, which have absolutely nothing to do with the appearance of their respective keys.