That's uhh, not what that says. One of the two mentions of half life are your body converting cyanide into thiocyanate, which will kill you and depending on your last bowel movement, make your corpse into hazardous waste itself.
The other mention is hydrogen cyanide in air, which is lighter than air and will decompose back into cyanide eventually, scattering it over a large area. Which will technically make it go away from your site, but spreading toxic waste over the countryside is illegal for a reason.