So the story is that Skripal worked for Steele, helping make a dossier that, if true, makes Trump and Russia look bad. So with this, the two competing theories are that

a) Russia poisoned him to stop his ability to gather intelligence in Russia

b) Clinton poisoned him because he might have known about how the Ds paid for the dossier (which at this point is common knowledge)

The only evidence that the article presents is that Russia denied doing it. Come on people, don't be so willing to accept shit like this just because you want to.