The suspension still works when you stand on the pedals. Think of the system as a beam with a sprung hinge in the middle, supported by the wheels at the two ends. When you're putting your weight on the saddle, you're effectively pushing down on the front half of the beam just in front of the hinge. When you put your weight on the pedals, you're pushing down on the rear half of the beam just behind the hinge. Either way, you're going to bend the beam. The suspension rate might change slightly, and there are a bunch of other reasons why a URT is shit, but it doesn't suddenly transform into a hardtail as soon as your butt lifts off the saddle.
ftfy
The suspension still works when you stand on the pedals. Think of the system as a beam with a sprung hinge in the middle, supported by the wheels at the two ends. When you're putting your weight on the saddle, you're effectively pushing down on the front half of the beam just in front of the hinge. When you put your weight on the pedals, you're pushing down on the rear half of the beam just behind the hinge. Either way, you're going to bend the beam. The suspension rate might change slightly, and there are a bunch of other reasons why a URT is shit, but it doesn't suddenly transform into a hardtail as soon as your butt lifts off the saddle.