Again thinking just the obvious thoughts to get them out of the way, there is from his perspective an obvious angle of attack that is suggestive of progress on both problems.
Physics as Civilization knows it is simple. Simple theories are more likely to be correct. Simple theories are not certain to be correct. If you tracked planets through the night sky by eyeballing their motion, the theory you would invent to explain them is classical mechanics, which in some senses if not others is simpler than General Relativity. But classical mechanics is false and General Relativity is true. A simple theory that excellently fits all the evidence you know is not always correct. Something very much like it is essentially always correct. General Relativity is like classical mechanics and that is why it gives nearly-classical motions to planets. But the actual simple theory is not necessarily correct.
Imagine a set of rules of physics which is like the physics that dath ilan knows, except that it contains some additional terms or downright if-then-else statements whereby two otherwise distant regions of space-time-configuration end up causally related. Sufficiently related, indeed, that a damp cave on another planet with breathable air, could end up causally descendant from the moment of a crashing plane in dath ilan.
These laws of physics are more complicated; they should end up with less measure in Greater Reality. But if their exceptional conditions have no influence at ordinary energies in a place like dath ilan, or if their if-then-else nature is not triggered within dath ilan, these universes of weird and complicated physics may have a dath-ilan-subpart which moves in exact synchrony with dath ilan.
Othrem's plane having crashed and truekilled him, all of him within the simple universes is gone; he continues, then, in much tinier measure, within the sort of complicated universes that have exceptional conditions that can trigger and materialize him inside a cave.