Mustachianism isn't about being frugal. Mustachianism is about optimizing for happiness. Frugality can be a part of that for many people, but isn't universally applicable.
Most of the earlier MMM posts are targeted at an audience in the accumulation phase, who have little to no retirement savings, who are spending money unwisely, and who are unhappy at least in part because of that unwise spending (racking up debt, lots of monthly payments, living paycheck to paycheck, etc). For people in that situation, the "get a used minivan, quit the starbucks habit, and shop at Aldi" advice is probably right, since doing so will reduce stress from feeling financially strapped, tied to a job, and feeling like they're going nowhere.
But that core tenet of optimizing for happiness means that for someone in MMM's position (retired early, no debt that can't be easily paid off, mindful spending), the advice can be exactly the opposite. Yes, you can buy the Tesla, the Starbucks, *and* the Trader Joe's bread, if that's what makes you happy. Because doing so won't bring on the negative consequences that people in the first group are dealing with.
EDIT: a couple proofreading errors