It's a logo not a paragraph of text. The overall image is supposed to convey the brand and not just a piece of it. Even W3/WCAG agrees and logos are exempt from the contrast requirement. So your whole argument of citing WCAG is irrelevant as it explicitly doesn't apply to logos.
It really depends if you consider "WASI" as essential to the information conveyed in the logo. Or said in other way: if the logo intent is to be readable.
I don't see how that link is relevant. Essential in that link simply indicates, as I read it, that the specific way the text of an image logo is rendered is essential to it's function. In other words that you can't simply replace the WASI in the image with the text "WASI." Essential does not mean that is must meet some requirements or be readable. In fact the contrast requirement your presentation cites is explicit in that it doesn't:
What does this mean? How does this relate to current logo? Is this a color blindness issue?