Would it be for this reason he did not exercise the options? 

According to Zacks: https://finance.zacks.com/blackout-period-8161.html

"If you work for a company that's publicly traded, you could be subject to blackout periods during which you're not allowed trade the company's stock. You might have access to nonpublic information, with a potential for illegal insider trading. A blackout period is generally part of a company's internal policy. It's meant to prevent corporate insiders from unfairly benefiting – intentionally or inadvertently – from trades in the stock market."

Koo