He's Andrew S. Tannenbaum, and you're Linus Torvalds. Think about it, and accept the challenge.

You never know OP, it could be what he's looking for. Maybe he's sick of being kisses up to. I mean, you might have gone against the grain but you never know it might work out in your favor

This is not necessarily a bad thing. He may appreciate the challenge to convince you otherwise.

I had a friend who got an interview at Oxford University and spent some time during it unknowingly slagging off a paper written by the interviewer's wife. Needless to say, he wasnt offered a place there. Subjectivity sucks, FYL.

Well, I would appreciate it, if I was him. And you know what I would appreciate even more? Your paper sent to me (the professor) directly, not just to the department.

It might not be all that bad. Some professors enjoy when they are challenged because they don't care that you disagree with them. They want to make you think and challenge yourself

It might work out in your favor, maybe he'll respect that you're challenging him.

He'd probably look at that positively, honestly. Many professors love professional critique

If he was good at his job he would take the criticism and apply it to his theory

He should be able to handle criticism.