It's a critique of the logic embedded in the definition you're using. You said earlier that being a professional or in management is "pretty much the definition of middle class." That is treating class as a static category tied to job role and income, not history, autonomy, or access to power.

My point is: when you define class that narrowly, it becomes easy to dismiss systemic barriers people face once they gain a bit of success. It makes it seem like they've escaped and no longer face structural disadvantages, which just isn't true for many. Especially when policies like IR35 are designed to push them out of ownership and back into dependency.