:hmph:
No.
This isn’t true, especially since you see the G-Man at the very beginning of the game, before you even kill anything. He also, you know, sends you into stasis, teleports you around, etc…I don’t know any government official who can do that.
Also, I believe that Valve had a fairly clear idea of the role the G-Man would play if Half-Life spawned sequels. Not some last-minute pawn to make the ending more interesting.