He maybe right. If were you, I'd had my boss review before I sen

Sounds like this is a highly political project. In such case, I'd like to have any cross group communication reviewed by my boss, or at least verbally talk to my boss about what I am trying to say, so that to make sure me and my boss are on the same page. If there is anyone challenge my decision in the future, it is not a suprise to my boss and he can back me up.
Your coworker may be a nice guy who want to help you. Also, it is important to remember that the person who gives you constructive feedback to you personally, is most likely a nice person and your friend. If he is your enemy, he'd talk to his boss or your boss, and stab you at your back.