Chelation therapy OK after tattoo removal?

You ask an excellent question here.
True, some pigments are salts of heavy metals, and it’s true that laser removal breaks larger crystals into smaller ones. The smaller crystals do not, however, release free heavy metal ions into the circulation (blood or lymph) so there is nothing really to chelate. On their way to excretion these fragments will remain just as inert as they were when they were implanted into your dermis.
Side note: The bigger “challenge” to your body’s filtration systems was the day you got the tattoo, not the removal treatments, but tattooing still appears to be quite safe.