It sounds as though the LLC structure was used for the purpose of concealing the real nature of the sale which appears to include a substantial gift from Trump to his son Eric. By doing this, were Trump to get away with it, he would avoid having the amount of the gift in excess of 14K charged against his lifetime estate tax exemption. If this is true, than the transaction, once exposed, will not be allowed shelter behind the veil of an LLC. The Trump LLC may have also claimed a capital loss on the sale! We will have to wait until Mueller's boys are finished with examining Trumps returns and finished questioning witnesses under oath. Let's wait and see what happens, shall we.
I expect this is just the tiniest tip of the Trump Tax filings iceberg. Who has the more competent attorneys do you think, Trump or Mueller?