The other, more immediate, problem with this type of thinking is that it's unlikely to change anyone's mind. I doubt that very many Trump voters will read this news and think: "I was influenced by Russia when I voted for Trump." They, like anyone casting a vote, felt they were voting for someone for their own reasons based on their own research. The most common reason I've heard for people voting for Trump is that they felt it was the only way to make their voices heard. Saying that no, actually the only voices that's being heard here is Russia's and thus it's illegitimate seems likely to make people feel the same way in 2020.