Why not carry 600 lbs of gold bars out into the forest and bury them, then hope nobody thought it was suspicious to see someone carrying a shovel into the forest on any one of the trips necessary to do it?

Because, for someone with any kind of security clearance, suddenly going out to the woods, if you don't normally go out to the woods, would be a major outlier from your highly-scrutinized and documented regular life; and so could easily lead the FBI to finding your buried gold, without having to get any kind of warrant.

Why not make multiple trips to carry extremely heavy metal, as a frail office worker, into the woods, which are full of hikers and hunters, on country roads in a suspicious-looking sedan, with a shovel in hand? And then do it all over again whenever you intend to retrieve these gold bars to do whatever it is you want to do with them? Why indeed.