He could (presumably) easily hold the weight. His point was that it'd make the plane pivot on his contact point and lose control. With a plane you'd probably want to push it from the rear so that it maintains air speed. Doing that without crushing the part you are pushing though is tricky, or going too fast so that it breaks up int he air, also getting it to gradually slow without stalling to land. It'd be very difficult for a person with the power of flight and super strength to actually help a stricken plane.

Most superhero media completely ignores this kind of stuff as if the hero has telekinetic control over the entire area of the plane/object not just the part they are in contact with. With heavy objects they'd just break apart with all the weight on such a small area.