(Bad metaphor. Antifreeze is tasty. lots of dogs are poisoned because it tastes good. But I take your point.)
His posts are/were superficially positive but most were engineered to elevate his status as the supreme fan or whatever you'd like to call it.
Antifreeze is tasty but drinking it is toxic.
Seems like the perfect metaphor to me, but regardless, the guy was toxic and wore out his welcome a long time ago.