It seems unlikely that the plaintiff would succeed on this matter as Burger King made it fairly clear that the Impossible Burger would be cooked on the same grill as meat and offered grill free cooking alternatives.  

A spokesperson from Burger King stated at the launch of the Impossible Whopper that “While the Impossible Whopper does not contain meat, it is cooked in the same broiler as our beef and chicken.”  

Additionally, the Burger King website lists eggs as an allergen of the Impossible Whopper, which are not eaten by vegans.

While it may sound a little disgusting, Burger King even provides an option to microwave the burger separately. Burger King has not claimed these are vegan and its website states "for guests looking for a meat-free option, a non-broiler method of preparation is available upon request." 

Dana Worth, Impossible Foods' head of sales, said in a recent interview. "For people who are strictly vegan, there is a microwave prep procedure that they're welcome to ask for in any store." Impossible Foods also said the Impossible Whopper was designed for meat eaters who want to consume less animal protein, not for vegans or vegetarians.