He is calling for peace. If he promoted more war, like the US politicians do even as Ukraine's soldiers continue to suffer, I could see your point. Yet, he is pointing out what many other's have pointed out -- that NATO is not a defensive pact, but an offensive machine. https://www.newyorker.com/news/q-and-a/why-john-mearsheimer-blames-the-us-for-the-crisis-in-ukraine