Since Steam started accepting BTC, I've bought a game or two with my coins.
But usually I prefer not to spend Bitcoins and use fiat instead.
I would say that you should control your spending your bitcoin for buying games on steam. Because if you run out of funds for this halving.
Then you are going to miss the chance of earning as you are holding your bitcoins.
He just try to buy games on steam since that company accepts bitcoin as their mode payment. Also I doubt he will spend all of his coins just to buy games on Steam since he stated that usually he wants to use fiat. But even if that will be the real score, I see no wrong here. It's his coins after all so he can do whatever he want disregarding all price trend that will happen.