Khan can prevent Fernando from protecting his allies with Commander's Grab. It will cancel his shield and displace Fernando behind Khan, meaning he must waste his Charge ability if he wants to be back in the fight.

Khan's ultimate relies on line of sight to grab his desired target, pull up Fernando's Shield and block your allies with it. Khan cannot grab any targets behind Fernando's Shield unless he has already fired his ultimate.

Khan is usually only a threat to the backline when he has his ultimate. Stay behind or inside your Frontline's shield to prolong or avoid Khan's ultimate completely as he cannot grab anyone behind a Shield.