Yep but he chooses for it to be restrict this way
I mean, you could say that groceries are part of your net worth, and immediately after purchase are roughly similar in value to the money you traded for them. Obviously people don't tend to bother counting their groceries as part of their net worth, mostly because they go bad or are consumed quickly and comprise a tiny percentage of most people's net worth.
But, in general, yes, your net worth is the value of everything you own (minus your debt). It's not at all crazy to say that, when you buy something very valuable or transfer money to a foundation which you control, your net worth is not changing much.
Yes, but that point comes when you eat the groceries, not when you buy them.