His point on dollar cost averaging is sensible. Markets go up, more than down, overall [the statistically best approach] if you have a lump sum to invest the best strategy would be to invest it all now. There is added risk with this however, which he would accept. Also it doesn’t change the main reason people end up dollar cost averaging (by default, with retirement savings from each paycheck).
He discusses these ideas, and many more in his book: Debunkery: Learn It, Do It, and Profit from It-Seeing Through Wall Street’s Money-Killing Myths.