LOTG, Yes, should have walked. might have been difficult to sell a VC for that but yes.
How often is it talked about or referred to as "what do the players want...." throw in, you are unsure, reds retreat, blues pick it up but you think it's a red ball ya de ya.
No one was looking for it, nor asking, and Giroud certainly didnt fall to the floor with the amoun of contact compared to the (IMO) lack of contact that Giroud made. Maybe if he'd flung himself to the floor rio may have walked, but did you lipread what Rio said to him?