If I understand the US Attorney's position correctly from the court documents, it is that anyone receiving a firearm with the intent of immediately transferring it to another specific person is guilty of a crime by virtue of the box check for 11a on the 4473, regardless of whether the ultimate recipient is a non-prohibited person or if a second FFL transfer occurs for the onward transfer. There may or may not be an exception for gifts between immediate family members. Again, I think this particular prosecution is motivated by a desire to get a defendant who skated on bank robbery, rather than a desire to stick it to gun-owners generally. Nevertheless, that is a very broad and dangerous argument to make.
I don't think that the defendant's misuse of Glock's "Blue Label" pricing was a factor in the prosecution. A key piece of evidence was a check from the uncle to the defendant, dated prior to the defendant buying the pistol, with "Glock 19" written in the memo line. The defendant cashed the check shortly after purchasing the Glock 19. Had the check been written out for $ 0.01 or $ 1 million, they would likely still have prosecuted because they could establish intent to purchase on behalf of a third party.