What are my options if I was hurt on job, surgery required, have open L&I claim and was fired after bringing note for accommodations such as sitting?

I was working when I fell. I hit my knee, went to the doctor and opened an L&I claim. I've been going to physical therapy and my doctor's appointments. It turns out that the injury cannot be fixed without surgery. My doctors put in a note that I need to have a sit-down position until I'm able to have the surgery. I went into work to turn in the note and start my shift and without even clocking in, they fired me stating that they didn't have the 8 hours in the budget for the reception area. However, I was still a full-time employee and they would have been paying me for 8 hours to do my regular job so it was in the budget. In the state, I thought L&I protected us from being fired, that they would have had to have a justifiable reason other than not in the budget. That they weren't allowed to make employment decisions while the claim was open. Shouldn't I have at least been on the clock when they fired me?