Because Cardano is what ETH might have been if done right. They did a tons of (actually scientific) research on the topics mentioned in this article but the author won't mention Cardano as it is his direct competition (even nicknamed Ethereum killer).
What does "actually scientific" and "real research" (mentioned by jki275) mean? I'm pretty sure most people doing research in the cryptocurrency space are trying to use the scientific method as much as they can.
To be fair, Vitalik didn't mention many research projects outside of Ethereum. I don't think he was intentionally ignoring Cardano, he just didn't need to reference them to make his points.
