[FirmwareBurner]

>I wonder what would happen if legal action started between two companies and it turned out a coder pasted code from personal projects that predates both.

Highly unlikely. This was no FOSS web library he was working on, but some relatively cutting edge embedded automotive stuff, which few people do in their free time as a side project to put on github.

And anyway, according to most industry contracts and work laws, whatever code you check in your employer's systems during work hours and using work equipment, automatically now becomes your employer's code which you now can't share anymore.