During the last economic downturn interest rates in a few countries fell below 0. This means that banks start to charge for holding cash instead of paying interest. I suspect that he feels that interest rates will have to fall below 0 at some point so holding gold is a good alternative to save money for future use. Another possibility is that inflation will eat up the money's value so gold is a good place to store value until needed. I say it's a good sign that Palantir does not need immediate cash and are able to meet their expenses near term.

Also, Google and Plantir are in 2 different phase in their growth. Google is unlikely to need cash for growth since it's making a truckload of earnings every quarter. Palantir on the other hand is likely to need some money in the future to grow. Gold is a great alternative for Palantir but not Google.