A word may function in several recognized registers. One might object that appealing to the convention of discourse makes the literal/figurative classification unstable, especially when the hearer is unsure which convention applies.
The answer is to distinguish recognized linguistic practice from a speaker’s arbitrary personal preference. An established convention supplies a meaningful standard; identifying that convention is part of understanding the utterance.
A word's literal status in one setting therefore need not settle its status in another. This is why context becomes important when separating accepted transfers of usage from temporary rhetorical transference.