The email was from 2015, but he had left Google in 2014, so it wasn't sent on company time/servers. Even if it had been sent earlier, Andy Rubin had been named

The email was from 2015, but he had left Google in 2014, so it wasn't sent on company time/servers. Even if it had been sent earlier, Andy Rubin had been named in enough patent lawsuits and deposed enough times to know that multiple plaintiffs had lawyers billing $700/800 per hour (at the very least) to go through all his corporate account's messages. He must have had tens of litigation holds.