He wouldn't even be charged for lying under oath if he lied and it became apparent, because there'd be not considering the much more serious espionage charges. They'd only prosecute the espionage part.

Participating in a plot to supply french state information to the US is espionage. France also apparently has a broad definition of espionage, relative to some other EU countries.

States have a tendency of coming down rather harshly on this kind of thing, so this idea about negligence is I think unlikely. If you know about it the charges will be espionage charges. If it happened it would be the biggest thing ever. They'd arrest most Microsoft employees in relevant teams as well the leadership, probably many others too. Just interrogation would probably take half a year due to lack of interrogators.