Diesel, your argument is flawed in several areas, that I will point out.
1- They can manufacture mags of a legal size with no problem, which they already do
2- Even if the "sale" is banned, the manufacturing is not (Big difference)
3- Transportation of any size is not illegal, it reverts back to "sale" only
4- Your argument about the state caring about the employees is also wrong. It is not the state that is moving the company, rather the company itself. It would appear the company's action would almost boarder extortion.
5- In essence, there is no limit to what they manufacture. only sell.