Well, you see scammers disappearing with coins everyday. If he really wanted to, he would just have to wait until brick-and-mortar stores or online stores accept BTC as a form of payment and he could spend those BTC directly there, no need for selling them first.
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.