As tastemaker status there are few as popular as Radiohead, especially Thom Yorke or guitarist Jonny Greewood. Any endorsement from them is likely to increase your popularity so I think it's respectable Greenwood lend himself to create this compilation for Trojan Records (the Motown of Jamaican music). It will undoubtedly shed new light and bring interest in musicians that definitely deserve it.
As for the mix, it's great. You would imagine that Greenwood would pick mostly dub or more experimental tracks but that's not the case at all. Lee Perry and Scientist are present, but besides that it mostly consists of soulful rocksteady and reggae tracks ranging from artists such as Lival Thompson, The Heptones, Desmond Dekker, and Marcia Aitken.