Most mathematically-competent commenters agreed that the expected utility of lotteries was bad. Some people disagreed that the utility of expectation was bad, though. Yudkowsky was arguing against these commenters, saying that both expected utility and utility of expectation are bad. The arguments in the post you linked are not the main reasons Yudkowsky does not play the lottery, but rather the arguments that convey the most new information about the lottery (and whatever the lottery is being used to illustrate).
Most mathematically-competent commenters agreed that the expected utility of lotteries was bad. Some people disagreed that the utility of expectation was bad, though. Yudkowsky was arguing against these commenters, saying that both expected utility and utility of expectation are bad. The arguments in the post you linked are not the main reasons Yudkowsky does not play the lottery, but rather the arguments that convey the most new information about the lottery (and whatever the lottery is being used to illustrate).