In essence the higher ups were sick of anthromorphics and wanted to focus more on "Human" characters, and were close to the point of firing him. However, most of the Industry was involved with WW2 so anyone they wanted to replace him with were too busy to work for WB. Jones realized this, so he made this short as one giant middle finger to the heads (said to be caricatured via the three Dover boys) as a way to say, "What are you gonna do fire me?, my work pays for your coke." He further agitated them by making this the first work to use "smear" animation as a form of fluidity, which they saw as childish.
tl;dr Three heads pissed at Jones for his degeneracy, degeneracy wins in the end.