It is 100% garden-variety pedantry. Everyone knows the meaning of "work for myself" and no-one is confused about to whom one has obligations. This entire thread is just "well ackshually whoever pays you is really your boss when you think about it!!"
Do they? I would disagree that everyone knows what that means. "Work for myself" often just means "nobody can boss me and I can work whenever I want" which is not the reality if someone pays you. Some of the most stressful and least flexible jobs are one-person businesses working for client.
It marks the difference between working for a single employer, multiple customers, or yourself.
If someone pays you, you're working for them.
So working for yourself means you don't have to listen to anyone but yourself when delivering.
This is possibly more utopian than what the author wants, and pointing out the difference is not pedantic.