>Would some middle manager involved in poaching this guy from the competitor want to do it? I have my suspicions.No company or manager I ever worked at, at both good and bad companies, would even think you'd be bringing stolen proprietary IP from your old job let alone allow something like this to happen under their nose with their knowledge.
They're far too afraid of IP lawsuits, as knowledge of the use of stolen IP can easily leak, and you then rating out that manager making them an accomplice, for anyone to allow for something like this to happen with their blessing. And plus, you never want to hire IP thieves, if they stole source code from their old job they'll steal from you as well.
>How was he hired?
Most likely Nvidia poached the guy on the premise he's gonna build form them something very similar to what he was working on at Valeo. The guy probably sold himself well to get the senior job at Nvidia but most likely knew he overpromised and would underdeliver, so to make his life easy at his new job, he took all the sourcecode and documents from his old job to use at is next job.
>How did he introduce the code into Nvidia's version control?
Well it's not like he was dumb enough to just dump in git all the stolen source code from Valeo with all the headers, variable names and copyright notices and nobody would notice. Most likely he kept the code on the laptop as an offline copy and only used it as inspiration for the code he wrote for Nvidia or maybe he even bluntly took Valeo's source code then pruned, redacted or renamed any and all references to Valeo and checked it in as Nvidia's project so nobody was the wiser that the code was not originally written by him.