A seated surgeon can operate on the hand and arm. In fact, that's the way everyone does it. The surgeon's knees easily fit under the small table holding the outstretched arm. Certain anorectal operations and gynecologic procedures done through the vagina can be done by a surgeon who is sitting, but abdominal and pelvic operations done via laparotomy can't be safely done that way.
The problem is that when a surgeon is sitting, she can't get close enough to the OR table and the patient to see way down into the abdomen and pelvis. If bleeding occurs deep in the wound, controlling it would be challenging to a surgeon who is sitting. Tying a secure knot in the pelvis while sitting might even be impossible.
With the exception of robot-assisted surgery where the surgeon sits a console remote from the operating table, a seated surgeon would have trouble doing both open and laparoscopic procedures. Even with a robotic operation, there can be problems. If the surgeon can't stand, an assistant would have to help insert the robotic ports. What if something went wrong and the abdomen had to be opened?
In a laparoscopic case, the video monitor could be seen by a sitting surgeon, but manipulating the rigid instruments would be difficult because of the angles created by the locations of the ports through which the instruments are passed.
As a retired surgeon, I sympathize with anyone who might be forced to quit operating because of illness or disability, but the safety of the patient comes first.
I hope that the suit is resolved quickly and we learn what the outcome is.