Several Engineers have pointed this out before - as have I:
Why do our bot-heals use BioMet? I hear that the brain of the bot is organic, but the brain is a very small part of a bot's total mass. Use MatMet/MatCrea instead, a much more logical skill-combination to apply to a damaged bot.
After all, BioMet only affects living tissue, and a bot is 99% inorganic material.