A Limited Liability CORPORATION is a person - by law.
Meaning post-86 toys are off limits unless you are an SOT.
A UT, by definition NOT a person according to the BATFE, CAN own Class III post-86 firearms.
Hence all the excitement. The ATF can't arbitrarily change the definitions without getting new legislation. So their initial approval, and subsequent attempt at revocation, is kind of a huge deal.