The thing about opossums is that they are notorious for not biting. Their defensive behaviours are hissing, running away, and playing dead.

Anecdotally, I've only ever seen one piece of footage of a caught opossum biting - out of hundreds of videos - and it was because the guy was holding the opossum my the scruff and sticking his finger in its face. This is why i believe those reports that oppossums aren't likely to hurt you, and why i said what I said earlier.