Changing IT systems is only part of the issue. The ultimate decision has to rest with the cabin crew and they must be supported in their judgement. If they deem a passenger is unsuitable for an over wing exit, then that decision has to be final. If CAs know they will always be supported, they will adhere to the spirit of their company's regulations. Unfortunately, there are too many instances of the cabin crew saying one thing and being incorrectly over-ruled by others, including the flight deck.