Naw he seems like a good guy.  But when you are actively arguing a point and a person says, that is not what this thing means and you keep arguing without checking and you are wrong.  

You have chosen not to find out and you don't know what you are saying.  So you are 

Willful - actively making a choice
Ignorant - lacking specific knowledge on a thing

This is always worse when people are repeating what other have said.  I always say, trust no one, even me, fact check everything.  And there is a reason.  

To call a man ignorant to a specific thing is not an insult, it is not like calling them stupid.  I am ignorant to many things but I don't talk about them like I know about them.