Doesn't apply. See above post and this link.
Do you mean splitting hairs about the difference between "imminent" and "gathering"?
If that's what you mean, no, that is absolutely not splitting hairs. Two totally different definitions:
Imminent: About to occur; impending: in imminent danger; Full of danger; threatening; menacing; perilous.
Gathering: accumulating and becoming more intense; "the gathering darkness"; To accumulate (something) gradually; amass; To grow or increase by degrees.
No. The word "imminent" has something called a definition, and whether Bush said Iraq was an "imminent threat" depends on whether his statements about Iraq meet that definition of "imminent", which they don't, as becomes especially clear from his 2003 State of the Union address in which he said we shouldn't wait until Iraq becomes an "imminent threat".
Not all statements of the form "X is a threat" are assertions that X is an imminent threat. Again: "imminent" has a definition.