I've never made BRITU. But... from what I've heard, the rub is very salty. You could just sub in the same amount of MSG as salt. if you want to compensate (not sure if it would need it) then use a bit more rub.
I have been making britu ribs for about a year now. My wife suffers the same as your wife. I have not ever put msg in this or any rub I have made. I don't add anymore salt than the recipe calls for and have never recieved a complaint on the ribs. They are very good and I love this recipe/technique.
Maybe I should try it with the msg to see what if any difference there is.
