Generally,
Short call: Bearish bias.
Short put: Bullish bias.
He shorted deep ITM put before AAPL ER -- he was basically betting that AAPL will rise sharply after ER. That was a bullish bet.
Before making a directional bet like this, one always has to ask how deep your pocket is, and how much you can afford to lose. It's not a risk free bet, although in hindsight it may appear to have limited downside risk.