He’s right. The Obama administration wanted to make these changes, so they asked congress to pass a new law clarifying the definition of a receiver. That was 2016.
Guess the joke is on the Joetato and his puppet masters then, because that means an injunction against the new rule should take about 15 minutes to get for exceeding statutory authority.
It's even funnier because some circuits have already held that the GCA definition does not match either a complete AR upper or lower.
The danger is that the current crop of Dem scum in control of Congress could try to write a more expansive definition.