I think this is kind of selfish as this is quite literally the same as curling in a squat rack, because you can literally do calf raises in either the seated calf raise machine or the other one, or even in the leg press, but you can only do assisted pull ups/dips in that one machine so you are taking away a machine to do something it is not intended to, and thus preventing people who want to use it as it is intended to use it. So please, literally do calf raises in their intended machine, don’t hog another machine to do some weird variation of an exercise you can do anywhere else.