If someone bought a cyber-truck without the Grock, they bought it as it was. Shoving Grock down the consumers' throats without their consent would constitute a material alteration of tge car that was originally bought. This would then constitute graffiti.

Edit: if the vehicle had not been fully purchased and paid, this would be potential grounds for a refund because the material alteration of the good would make the contract for the sale of the vehicle voidable.