Why Modern Mickey is in the Public Domain

The first appearance of Modern (Fred Moore) Mickey was in the 1939 short "Mickey's Surprise Party" made for the NABISCO corporation, this short is now in the public domain. Similarly, Celebrity pictures, the distributor of the Mickey shorts used this poster from 1928 to promote the initial batch of Mickey shorts, the poster included the gloves, red shorts, and distinct "pie eyes". As such, all elements used in the "modern" Mickey design were already introduced in some form in 1928. Hence there is nothing outside of Mickey's modern voice that is not in the public domain at this point, as all other elements had public domain first appearances. I look forwards to any rebuttals.

Poster from 1928

Mickey as he appeared in \"Mickey's Surprise party\", the first appearance of \"modern Mickey\".