AFAIK, the JW's have never insisted that either the cobra or snakes in general have literal ears that can be "stopped up" despite what the Psalm says, so the JW's are clearly not adverse to more reasonable explanations.
A JW veterinarian pointed out to them once that the restoration prophecies only state that domestic animals (e.g. sheep, cattle, goats) and people would be safe from predators and don't actually say a word about wild forms of prey. Her suggested that since "dust" as the food of snakes (Isa 65:25) can't be taken literally, then perhaps they were reading more into the verses than what was warranted. He gave many more examples of how literal interpretations contradict arguments for creation and how examples of "Jehovah's wisdom" that JW publications routinely pointed to (i.e. shark and remora, oxpecker bird and rhino, scavengers of all types, etc.) could not have been designed under that model.
In the end however, he had to acknowledge that the one thing leaders and policy makers truly hate is a smartass.