Author's comment about selling Puts being somehow riskier ("subject to margin calls") than Covered Calls is incorrect. All things being equal (say, same account size, same strike prices, and same number of options traded) the risk is exactly the same. As long as the notional value (number of options multiplied by strike price) of your Puts is equal or grater than your account's remaining cash balance, you will NEVER get a margin call.
Profiting from Risk Aversion [View article]