They dont put warnings on the labels of ALA because it is simply an antioxidant. It is not the most known stuff to be used for chelating mercury. So they are not at all obliged to do that.

If it works for a person that is good, but it can really hurt some people with amalgams or without becuase it can shift mercury into the brain if they have not first reduced their body burden. Simply because it can cross the blood brain barrier. This is great later on to remove mercury from there, but not so good if you're still high in mercury elsewhere (blood etc). Should also be used in a proper manner to ensure less redistribution and safer removal.

But again, some seem to do ok on it regardless. It is beneficial because it is good for the liver and increases glutathione levels in the body etc. But it's a good idea to be cautious in my opinion.