Being a big, and longtime fan, of both MMM and Tyler Cowen (Marginalrevolution.com), I would step up and defend Tyler just a bit. It seems to me that he didn't spend much time learning what MMM is truly all about and just read "High Savings rate so that one can retire early in order to sit around and do nothing." And he is right, many people who stop working altogether don't have the curiosity, hobbies, and personal discipline that MMM has to productively pursue other interests. No judgement, that just seems like a relatively uncontroversial observation. There is a significant, non-zero number of people who retire at 65 and are less happy post-retirement than pre-retirement (I, of course, am using the word "retirement" here to indicate the traditional type of retirement, I am not part of the Internet Retirement Police brigade).
I'm sure not every reader on here completely got MMM the first time they read a post and Tyler Cowen is no different than the rest of us. He blog isn't a policy paper or academic paper, it is to post his thoughts on just like this forum. He even qualifies his statement with, "If I understand him correctly, he recommends a very high savings rate and very early retirement", indicating that he might not be understanding MMM correctly (not exactly "fuzzy thinking"). And he appears to have linked an addendum to the original to clarify.
If you want a blog that has a fair amount of original, non-partisan thinking (sound familiar?) on topics ranging from the money supply to where to get good ethnic food in Birmingham, AL, I recommend giving Marginal Revolution a chance.