alt Hacker NewsBut do we usually describe cats as comfortable, as in their feelings? We might say he IS comfortable, or he feels comfort, but for something to be "comfortable" that implies it gives comfort to others. I can see a cat being comfortable to a human, in that a cat gives comfort to a human. But I wouldn't say "The cat is comfortable, therefore he laid on a mat." Its almost a garden path sentence, I would expect "The cat is comfortable, that's why I let him lay on me".
In literary and casual contexts, absolutely (though we'd probably say "he/she" instead of "it" here). As I said, "it" referring to the mat is the most natural and obvious reading, but other ones are perfectly logical and sound, if less likely/common.
Although the sentence is itself a bit awkward and strange on its own, and really needs context. In fact, this is because the sentence is generated as a short example to make a point about attention and tokens, and is not really something someone would utter naturally in isolation.
I mostly just wanted to playfully comment that original GP / top-level comment had a valid point about the ambiguity!