I think you've missed the author's point: she's drawing a distinction between actually being busy (non-self-imposed workload) and telling people you're busy (self-imposed workload). The preceding sentences for context:

Notice it isn’t generally people pulling back-to-back shifts in the I.C.U. or commuting by bus to three minimum-wage jobs who tell you how busy they are; what those people are is not busy but tired. Exhausted. Dead on their feet. It’s almost always people whose lamented busyness is purely self-imposed ...

Working two jobs and rearing three kids is actually busy. Coaching little league and noodling about on HN, on the other hand, is self-imposed.