How is adding additional layers of security bad when there is a specific attack against one of the layers of security (timing attack via controlled TOR nodes) t

How is adding additional layers of security bad when there is a specific attack against one of the layers of security (timing attack via controlled TOR nodes) that a VPN-to-Tor would disrupt? If this method is dependent on knowing the latency going in and out of the network, adding VPNs that have varying latencies would seem to defeat this on the surface. I'm posing the question, as I don't see an answer in the article. Nobody gets better at opsec if flawed methodologies aren't picked apart in detail. I'm surprised I was downvoted, but I don't comment here frequently and maybe didn't pose the question in enough detail. This is usually how I was accessing Tor based on the assumption that most of the exit nodes are compromised.