Did brother of Goofy creator's employer commit an excommunicable offense?
A step-by-step solution is:
yes
Goofy was created by Art Babbitt who worked for Walt Disney.

Walt Disney's brother, Roy Disney, was a member of the Freemasons.

The Catholic Church has a litany of offenses that can get someone excommunicated.

Being initiated to Freemasonry, is listed as an excommunicable offense.

.

Thus, the answer is yes