Actually, you would be wrong, well, half wrong. Why would you put life support on the pel'tak? On Ha'taks, that system can be controled from the Pel'tak sure, but she went to the system itself and sabotaged it manually. As has been seen many times before, engine room access often overides orders from the Pel'tak, whereas if you outright sabotage the system, its not going to be overridden.

And she didn't sabotage the hyperdrive itself, which is definitely in the engine room, merely the control that would let someone in the Pel'tak activate the engine. Like cutting the line between the accelerator pedal and the engine on a car. The engine is fine, and can still accelerate, but pushing the pedal won't tell it to do that. If someone was bright enough, they could poke around in the engine room and activate the hyperdrive, but since she was about to go there anyway, safer to cut control systems rather than mess around with the drive itself.