Generators are ~30% efficient and Starlink takes 100W. So you'll need 300 watts of production. But even maxing during weightlifting gets you only 400-500 watts, and nobody can max weightlift all day.
You can't power Starlink by muscle.
Starlink also does not have satellite to satellite communication, SpaceX admitted that it was too expensive.
, the frequency is mostly empty other than Starlink and some western satellite TV, the directionality is known since the satellites are being tracked in orbit at all times, and the phase is known because you can measure it with RF sensors. If you know frequency, directionality and phase, you can easily selectively jam the frequency and nothing else, at very low power. A jammer at 10 km distant can easily overpower a satellite at 500 km distant. And in fact, you can even use 12 GHz band for 5G (see article), which vastly overpowers weak satellite signals, so you'd basically have jammers simply for having 5G.
In summary - you can't clandestinely power Starlink, but even if you could, it wouldn't do you any good since it still needs ground stations within 500 km, but even if it didn't, it can still be jammed easily, and even if it wasn't, you can 'accidentally' jam it by simply using 12 GHz stations for 5G.