As a native English speaker, I disagree. I would view using that phrase to tell someone that their cat as been hit by a car as being oddly callous and uncaring

As a native English speaker, I disagree. I would view using that phrase to tell someone that their cat as been hit by a car as being oddly callous and uncaring and therefore I would be much more likely to interpret that phrase as expressing literal fear about an unknown fate. That interpretation is also much more statistically likely as people worry about missing cats more often than they are told they are injured. In practice, completely context free disambiguation is rare so when doing a thought experiment around one, it is easy to accidentally assume some level of context without realizing.