The mentioned size and density of Whitehead & Russel's Principia make the few dozen pages of Goedel's On Formally Undecidable Propositions of Principia Mathematica and Related Systems one of the greatest "i ain't reading all that/i'm happy for u tho/or sorry that happened" mathematical shitposts of all time.
Gödel had great respect for their work and was considered one of only a few people at the time to have read and understood the work. He wrote an entire paper later in life explaining he wouldn’t have come to his result without Principia because it showed him a base case to work from. Him and Russell would continue to meet and discuss logic well into the 50’s.
First, you’re arguing with someone making a joke, and second, yes, he understood the axioms very well and was able to use the system to prove his incompleteness theorems, but, citation needed on whether he actually read the full three volumes? Russell himself said that “I used to know of only six people who had read the later parts of the book. Three of these were Poles... The other three were Texans [Gödel was neither Polish, nor Texan]”