If you've been suffering acute IBS for months and can't get a regular doctor's appointment in that time, why would that not be considered a case for urgent care?
This whole store lacks enough detail to know exactly what's going on, however, so we're all going to project our biases on it. If you're anti-Amazon you're going to project your assumptions of unfair business practices. If you're skeptical of that position you're going to project your skepticism into the unknowns of the story. Really there aren't enough facts here to know if this is Amazon firing an underperforming employee who is lying about a health condition, or failing to accommodate an employee with a legitimate health problem.
