The Gallant range of table is one of the few things that Ikea made it good.
The strength of the wooden tabletop is provided by the stiff metal frame that runs the underside of the wooden tabletop. So unless the metal frame can flex, the table will not flex.
But I must add. While it will not flex, because it does not have a vertical backing, it suffers from lateral movement. You can shake the table and it will move from left to right but not front back.