"Strong"! definition
I know the Blue Book is under revision, maybe one should amend the rule slightly
Today my partner opened 2 clubs on 13 points - 8 clubs to the AKQJ and KX in spades. (They made 8 clubs and the Ace of diamonds that I kindly gave to them - opponents had bid spades but did not lead the suit and guessed wrongly): This hand qualifies as "Strong" under the meaning of the act.
I think the rule was such that the hand had strength in two suits and thus wasn't pre-emptive in nature, but should there be a minimum length in two suits e.g. 4+ so both are "natural"?

Comments
It's not clear to me what your objection to this is.
I guess that there's a qualitative difference between, say, a 6-5 hand with great playing strength and an 8-2 hand, which is very concentrated in the one suit. You do still have some values outside the main suit on the hand John quotes, and it's more than just a preempt I think. With the suggested tweak you might end up excluding some hands with stronger 3 card fragments or doubletons, AKJ to 8 and AK maybe. Or KQJ to 7 and AKQ even, that's only 15.
I've never really seen the problem with these hands opening 2C, so long as it's disclosed. Although it's a situation where you alert and that tends to be assumed to have a meaning, which is a separate issue to do with how the regulations work in practice.