Imagine a device that blows up when it ceases to receive a signal from an outside source, as you say. What exactly do you do with the Force in that case? You can't replicate the signal with the Force AFAIK. If you tamper with the bomb and interrupt the signal, it will go off. If you broadcast your own signal, well, you're broadcasting a signal and I imagine the Hutts would frown on that (it is a low profile mission after all). And that's assuming the bomb doesn't respond to a specific frequency that you don't know.Except that the explosives, according to Anakin, are set to blow if they leave the planet. Which means at the very least they have GPS level or some other form of transmitting/receiving electronics to some point probably in Watto's garage. At this point it's just a matter of finding a way to either replicate that signal so it doesn't go off, or disabling/removing the bomb itself.
Qui-Gon's not omniscient, nor omnipotent; almost no Force users use telekinesis with such subtlety. He has no idea what will happen if he starts poking around with those things.