It wasn't much of an argument for Postgres either. He said it had lots of features, kinda had speed, but oh wait those things don't matter because it works with Rails and MySQL got bought by Oracle.
Actually he also said that PostgreSQL has a permissive license with a whole community of contributers where MySQL has Oracle and GPL and 1 corporate contributor. That's a significant qualitative difference in their nature and very well worth weighing up if you're deciding which way to go.
