Is Dr Esselstyn crazy?

Dr Esselstyn is about 90 years old; has he gone senile? He recently recommends chewing on leafy greens all day. This is AFTER his great research studies on preventing coronary artery disease. He's been hanging around with the nitric oxide guy, Nathan Bryan Phd. Is it true? Does grazing on greens really increase endothelial nitric oxide, and tissue oxygenation? Why should we care?