(edit: not just having a sidegig, but being able to launch and run his startup for ~1 year while employed at Tesla)
I also have a low bar after reading "Bad Blood", the book about Theranos. One of Theranos's chief engineers, on his own time, came up with a cool idea for bike lights and ran a successful KickStarter [0]. Elizabeth Holmes' response:
> Kent told Elizabeth about his successful Kickstarter campaign, thinking she wouldn’t mind. But he badly miscalculated: she and Sunny were furious. They viewed it as a major conflict of interest and asked him to transfer his bike-lights patent to Theranos. The paperwork Kent had signed when he joined the company entitled them to any intellectual property he produced while employed there, they contended. Kent disagreed. He’d worked on his little venture during his free time and felt he had done nothing wrong. He also failed to see how a new type of bicycle light posed a threat to a maker of blood-testing equipment. But Elizabeth and Sunny wouldn’t let it go. In meeting after meeting, they tried to get him to turn over the patent. They ratcheted up the pressure by bringing Theranos’s new senior counsel, David Doyle, to some of the meetings.
Eventually Kent, the engineer, was allowed to go on leave of absence to work on his bike-light. I don't think he ever came back, and he was the guy who was the chief architect of the piece of crap that Holmes would later describe as "the most important thing humanity has ever built".
[0] https://www.kickstarter.com/projects/revolights/revolights-j...