Lacerations and injuries in the mouth generally heal really, really well though, so perhaps the saliva won’t actually impede healing as much as it seems like it could? At least it is “clean” saliva, and not goo with feed particles.
I am a little surprised that a drain wasn’t left in situ to prevent a pocket from forming in there, but this is just an observation from an armchair quarterback, and I’m sure the vet on scene has a better handle on the situation