None of the other contestants got ill, so that largely rules out bug poisons or other pathogens.
My guess would be he either had an allergy or some pre-existing condition.
Either way, that's irresputably discusting way to go out!
You do not examine legislation in the light of the benefits it will convey if properly administered, but in the light of the wrongs it would do and the harms it would cause if improperly administered. - Lyndon Johnson