Maybe he looked at her eyes while she was walking towards him and as he was being slowly entombed in stone, he decided to use his last bit of life to check out dat azz.
His last thoughts, the woman he looked into her eyes and froze him in time as she walked by he thinks upon himself and looks down at the earth to find where he may be. And there, there in plain sight, was her derriere. His final breath, his final moment, his truth, her derriere