It may not have been so much to protect you as much as a sarcastic commentary on the quality of the beer. It would be far from the first time I've heard or seen someone describe it as such (I don't drink alcohol due to not wanting to wind up like my abusive father, so can't comment personally).

About 20 years ago I was at a party and an old man was drinking actual water from Budweiser cans. They were silver or silver lighter color instead of red and were given out after a hurricane or some other natural disaster.