In WA state, L&I case manager states "debilitating pain is not a consideration"?

I have been off work since Feb '08 after work injury to my back, and am unable to stand or walk or sit for more than 10 minutes due to incredible pain. Driving more than 5 miles causes me to pull over and get out of the car to relieve the pain. Nonetheless, L&I says I can take a job as a courier and has stopped time loss payments before the Independent Medical Examination. Is this legal?