For-profit vs. Non-profit is an entirely different distinction under US law, with specific legal definitions for each. This is entirely separate under US law from publicly traded vs. privately owned, which has separate specific legal definitions.

Valve is a for-profit privately owned company. That is what allows it to not maximize shareholder value, and is the unstated distinction that allows your quote to be true.

For-profit publicly traded companies do have a legal responsibility for such.