I’m sure the BATF really hates that someone is “getting around the law” with the 80% complete receivers.
But, it’s actually complying with the law, and legally they can do nothing about it. As we see here, though, they disregard the law and punish the manufacturer anyway.
You can bet that democrips in the House and ‘Sin’ate are already working on wording to close the ‘loopholes’.