I was disappointed. I thought that Buffett's time, used to pick good charities, could be far more valuable than his money

I am not sure about this one. Buffett's skillset in picking very good investments, might not transfer to picking good charities. Or at the very least, he might need to spend some time practicing before getting good? Not to mention validation cycle time on charities vary(am not sure how much more than investments) and Buffett considered his time better spent investing, and not acquiring skill at charity picking?