The bulk email classic! Maybe he was trying to show that if you don’t give him an offer, sone of your competitors might, so act fast?
I wouldn’t do this because it would be mean, but it would be hypothetically funny to reply all with a fictions offer and start a mock bidding war.
So much of these things come down to relationships, it is really amazing. I think if a candidate apply the design process of research, empathize with a user, identify problems, and craft appropriate solutions, it becomes much easier to get a job. If you focus on the needs of the hiring manager and how hiring you will solve those needs, you quickly eliminate the bulk email from your solution set.