Exactly this. When you stop selling BTC for fiat and instead use it to buy products from brick and mortar stores, you are no longer devaluing bitcoin, instead, you are helping it grow, distributing it more, nad make it more viable as an everyday currency. This is what he would have wanted.
There are already many stores online and in the real world where he could spend his coins. Regardless of that though people would go crazy as soon as the coins moved anywhere and would spend a lot of time trying to trace them. They then likely would be able to be traced to the stores he used them at.
Yeah, I agree that Satoshi would have wanted people to spend Bitcoins in stores and use it for legitimate purchases and trades, but if Satoshi himself started to sell some of his early-mined coins, people would sure freak out, yes. This would prove that he still has access to a
ton of coins.