He doesn't say much in that article, this is the crux of it:
“There’s not a lot of roots in that music...What’s wrong with Sgt. Pepper? “Some people think it’s a genius album, but I think it’s a mishmash of rubbish,”
I suspect this is Keith's considered opinion. I'm not actually a Stones fan so Keith's opinion has little weight with me, but as to the substance of what he is saying. "Not an lot of roots" I just don't think Keith recognises the roots of Beatles music, for me it is more grounded than the Stones, the Stones tried to draw on African American Blues music but I think what the Beatles did was greater in that their music had more English roots especially with Sgt Pepper, so it was truer to who they were. There is plenty of Blues, Motown, Rock N Roll influence in the Beatles, but there is always the sense that this is all being channeled through a Liverpudlean sensibility. English culture has a very magpie sense to it and Beatles music is a massive conduit for it. The Stones to me are always trying to be something they aren't, they do it really well, but as far as being grounded and having roots I'd give it to the Beatles every time.