One of my Sims just got inducted into the Secret Society at Le Tour. Would putting any of the career rewards in his inventory be a VBT?
If your goal is to steal them, go for it. The game itself won't care if you've stolen the secret society's stuff, embezzled all their money, and razed their building to the ground.
Would the game regenerate them at the Secret Society lot the next time my Sim visits?
Nope. Damage and destruction inflicted upon the Secret Society lot is there forever. Mine is still full of Eau de Brynne from the time the Brynnes made it in, all the way at the beginning of the story.