He was swallowed whole by a Titan, right? So that means, like Eren, Thomas found himself stuck in it’s stomach among the bits and pieces of corpses floating around him. UNLIKE Eren though, Thomas wasn’t a Titan. So that means Thomas had no choice but to sit and wait to die.
And it’s even possible that the Titan went on to eat other people so other corpses would rain down on top of him!
HAVE A GREAT DAY.