As an example, I can say that Judo isn't Aikido because Aikido works on circular principles, and changing the circle's direction. Judo uses leverage. Or that one of the things that distinguishes Silat from many other arts is the emphasis on using positioning relative to the opponent more than using a lot of defined responses. I'm not asking you to provide a primer on Krav Maga -- but a few key things to look for to evaluate someone, beyond the IKMA "seal of approval" on it.
I'm still not fully understanding the question as it's comparing apples to oranges within the martial-arts world, but I will try to answer it to the best of my ability regardless. The "IKMA's seal of approval" has very little to do with making "legitimate Krav Maga" as there are many "legitimate" Krav Maga organizations besides the IKMA run by Haim Gidon (8th Dan Black Belt under Imi), there is the IKMF run by Eyal Yanilov (6th Dan Black Belt under Imi), as well as the KMF run by Haim Zut (7th Dan Black Belt under Imi). IKMF teaches Krav Maga, KMF teaches Krav Maga, IKMA teaches Krav Maga, KMWW teaches Krav Maga, FIGHT teaches "Haganah". Krav Maga works by using "small, simple" movements with little-to-no wasted motion and never uses "strength vs strength", virtually all of what we do is ment for the street and has little place in an MMA ring, Haganah, unfortunately does not follow these principles. If you'd wish to learn more about Haganah and/or Mike Kanarek you can look at the websites I listed previously.