That person doesn't sound very mustachian, saving enough to spend 100% of pre-retirement salary:
4. Maintaining your lifestyle isn’t as easy as it looks. After nine years, I’ve maintained mine. But that’s only been possible because of a measure of frugality, coupled with my goal of retiring with enough income to replicate 100% of my base salary, rather than the standard advice to aim for 80%.
By comparison, a semi-FAT FIRE for me involves saving enough to replace about 50% of my base salary with my barebones being less than 25% of my base salary.