thats true.
you mean like how there's supposedly a "maximum LOP rule of 13.5" before a brace or cheek rest becomes a "stock" "? Which was thrown out in a Ohio court because it was
not published anywhere, therefore the owner had no reasonable way of knowing whether or not his accessory violated laws and regulations...

thats
if Congress submits bills and so forth. Not holding my breath if Congress will stay basically deadlocked or not.
"not approved" basically opens up owners of said accessories to legal prosecution even if there's case law weighted
against the ATF. Again, if the ATF
refuses to issue opinion letters of approval from 2018-onwards
how are companies supposed to follow the ATF's most current statements, in that they need to have "approval letters" or to submit them for consideration, before selling them?

Look at what the link I provided says..
Emphasis added.