Yes Grealish does go to ground slightly easier than most, but then again if you watched him every week you see he is usually targetted for a meaty challenge within the first few minutes. Happened last night, happened against Leeds a few weeks back, happens when the other team try to nullify him by kicking him. You can argue that going down to win teh free-kick is gamesmanship, but then again so is going out to target a player by fouling him. One game, it may have been Cardiff last year, and against Bham at home this year, they took turns in who was going to kick Grealish and get booked for it. And not always do they get booked.
Players like Grealish need more protection - see Zaha at palace - but they don't get it. if they have to try and take some advantage back from the kickers then so be it. Its a two way street.