I've never had a cofounder like this, but I've (almost) had freelance clients who tried to start the relationship by sending an aggressive, strongly-worded, and one-sided list of rules. (Rule 1: You shall not be paid until final delivery. Rule 2: You must provide 24-hour turnaround; failure to do so will result in a $250 penalty. Etc..)

It's not about the money, but the attitude it demonstrates. It tips you off that the person will be unpleasant to work with, and imagines themselves constantly defending against people trying to take advantage of them.