Briefly:

show "some string"

results in the first character of the string being mistaken for a pointer to an integer and dereferenced on arm32 platforms (the zynq7000 platform seL4 supports for "simulation," specifically).

If y'all can get a clean fix figured out ahead of me, more power to you. Otherwise I'll be returning to this problem and posting a clearer explanation of this bug this evening, once I'm back at a terminal.