Retro install 737 "thrust levers"* where the G/A button is on top. Cost category - MX, $$$$$.
or
Put your arm on top of the "thrust levers"* while using the speed brake from the right seat, removing the threat of inadvertent G/A switch engagement. Bonus, one can feel the throttles, er, I mean "thrust levers" move at level off/power up and stow the brakes. Training, $
or
Don't hire people that should not be flying. High startle, low SA, overreacts with a crazy ivan vs a trained maneuver. Hiring, free; or Training, $ for starting and washing them out.
* Boeing and its use of weird terms for airplane things.