My new conspiracy theory
Saquon was never injured. The giants felt strongly they were going to win the game and had SB game an injury, hence the huge angry reaction on the sideline, have played coy all week about his availability because they know with the short week of prep, SF will have to choose to game plan either with or without Saquon and will default to the giants playing it safe with him. Giants come out with a full strength Saquon hoping SF has just spent several days assuming he was going to be out.