Kill switch is a possibility, but once you start adding more than one item to a cell it doesn't always work out. What I mean is that the number of cells that successfully take both edits and continue to operate normally or survive the editing process drops considerably.

You are correct that current cell transplant therapies exist, but I don't believe any before have contained these immune escaping edits and I believe all of those treatments are cancer treatments which allow for a different level of risk. Diabetes is a very serious disease but a quality of life treatment does exist and having cells result in a potential cancer in patients would not be acceptable as an outcome.