The first thing that you do with your cash flow is pay your people. Everyone gets paid after because without you people you are nothing.
Experienced and driven people are what attract investment, and they are what makes you profitable. Investors usually use you ideas as a formality but when they choose to invest they will be looking towards what kind of employees you can attract. That's the reason why Tesla's shares are at $181. Because Elon Muck has the drive, experience, charisma, and track record to get that investment, and no one cares if Tesla won't be profitable until 2020. Businesses can survive for quite a while without profits, but they die pretty fast without people.
Don't believe me then lets try an experiment with two businesses. In one case they don't pay their employees salary for a month and in the other they don't pay the shareholders for a month. See which one dies sooner.
As far as the stunt being for PR I don't think that is the primary motivation here. As I said before even with the stock options (based on the calculations of a previous poster) he is still slashing his salary from 2.2M to 400K. That is a very large drop in money for something that is just designed to generate PR especially seeing as how our spending budgets tend to grow to fit how much money we make. And even if his salary climbs again so what? He should be paid in proportion to how well his company is doing especially if he founded the the thing.