If you throw a grenade in the area of a CT, expect to get shot. And rightfully so. Even in your "innocent to proven guilty" argument, if you threw a nade anywhere near a police officer (or in general really) you're going to get shot. Same with knifing. You're welcome to knife the air, but if you attempt to knife a police officer the judge is literally going to throw a book at you if you argue "but I didn't actually harm him".
Role play aside, what reason do you have to throw a nade near a CT other than to harm him? Even if you didn't actually mean to, you just need to pay better attention to your surroundings and where you're throwing. Same goes for knifing, if you're chasing a CT and clearly in his face trying to knife him, there's no reason you shouldn't get shot.
Read the thread I made that All Ts linked to and if you still have any questions feel free to ask, but the rule isn't being changed.