So if a defender has the ball pushed past him by an attacker and decides the best way to defend is to dive head long in front of an attacker to stop him getting the ball he just pushed past the defender, then that's OK? As long as he times it right so the attacker runs into him
It's really simple, Saka is clear and well in front of the defender and is in the motion of shooting.
The defender cannot possibly get to the ball so sticks his foot in front of Saka... nowhere near the ball and entirely to stop Saka making connection.
This was NOTHING like a situation where an attacker runs into a defender.