[MeatyOakerSmoker]

The idea with botulinum is it was on everything from the second you got it. So it's not about it getting infected after the casing. My guess is you watched Franklin cook these things to a proper internal temperature.

Botulism is only a threat for uncooked foods and by uncooked I mean not brought up to a temperature high enough and for long enough to kill the bacteria and destroy the toxins. I'm pretty sure the latter is the most important.

Also I might be wrong here but I'm pretty sure the deal with casing is really that it restricts oxygen which creates the right environment for the toxin to be produced. Either way cooking makes it kosher from everything I know.