The website states there are different types of B12 and discounts your statement.
"While being a natural chemical produced in the body, cyanide is toxic, and the body turns it into thiocyanate in order to excrete it. If this pathway is defective or overwhelmed through ingestion of too much cyanide (such as in smokers, or people in Nigeria who eat large amounts of cassava which is high in cyanide), the body may detoxify the cyanide by attaching it to cobalamin and then excreting the cyanocobalamin. Leber's optic atrophy, tobacco-alcohol amblyopia, and other eye diseases can sometimes respond to high doses of hydroxocobalamin which serve to detoxify the cyanide. In these cases, there may be too much cyanide in the tissues (preventing conversion of cyanocobalamin to methylcobalamin or adenosylcobalamin) for cyanocobalamin supplements to be effective in maintaining B12 status.1 In such cases, a different form of B12 should be given (speak to your health professional)."