The [NIH RDA][1] for vitamin B12 is 2-3µg/day. Cyanocobalamin has an $M_r$ of 1355, of which 26, or less than 2% ($CN^-$) is cyanide. 

Since the [Minimal Risk Level][2] for cyanide is [50µg/kg/day][3], your studies are correct in that 1000x the RDA of vitamin B12 in the form of cyanocobalamin is not lethal, and furthermore is expected to not cause any negative effects even in the most sensitive of individuals. 

This holds true even if 100% of the cyanide ligands dissociate from cyanocobalamin, which is unlikely to be the case in practice due to cyanide being a very strong binding ligand. 

Cyanocobalamin contains too little cyanide, and is consumed in too low an amount, to cause cyanide toxicity. [The dose makes the poison][4]. 


  [1]: http://ods.od.nih.gov/factsheets/vitaminb12
  [2]: http://www.atsdr.cdc.gov/toxprofiles/tp8-a.pdf
  [3]: http://www.atsdr.cdc.gov/toxprofiles/tp8-c8.pdf
  [4]: http://en.wikipedia.org/wiki/The_dose_makes_the_poison