as others have stated that is the point of having shift key, just like playing competitive, your not wanting to be found because you walk to loud... it keeps it more intense in who will find the back of who, plus like "hello?" stated shift walking isnt the main cause of delaying its mostly because, some people havent read the rule, or they want to be last one alive... etc the list goes on.
Plus like Damon said, its really hard to implement something thats csgo coded to disable an action of a movement of the person
for that reason im sorry but -1