Sure. But if bitcoin is the defacto currency then they can just put enough into circulation to make the bit of BTC they spend to be massively expensive and pay for whatever they need, while still having enough to do massive projects that they want to do (or not). Could also die and have the coins locked forever.
Discussion
Yes, but by limiting spending they limit the amount of stuff/influence they can buy. The point is, once you spend it, you can’t create more unless you provide value to others. To your second point: that would be awesome. Let’s say I own a million bitcoin. If I die and don’t pass it on, this means that these 1 million bitcoin will never be sold on the market again. It’s basically a donation to everyone else that holds Bitcoin, as contrary as it may sound.