If you compost mint (spearmint or other mints) that has set seed, than I can see how you could "contaminate" low temp compost in that there's not enough heat in the pile to kill the seeds. This would apply to ANY plant that you add into that pile that has already set seed (especially any member of the Brassicaceae).
Whether you inadvertently sow seeds with your compost is more a factor of seeds being on the plants that you add to your low-temperature compost than the type of plant in the compost. I've "sown" Ampelopsis, Actaea (specifically red baneberry), Lychnis viscaria, and even Johnny Jump-up simply by adding compost to my vegetable garden. This is why I never include seedheads when I add plants to my low-temp pile.