As far as I can see you play a false nine when your wide inside forwards are better finishers than your central striker (mane and salah).
We’ve got two strikers who are known for their finishing and goal poaching. Why would we want to take either of them further away from the goal in favour of getting our wide players, who are known for being able to pick up the ball deep, beating a man and/or threading a through ball, closer to the penalty area.
With the personnel we have, playing a false nine is amongst the last things I would consider.