Flipped him, as in converted him to her plans, or offered him something he wanted?
Seska had no sensible plans. Was she planning on creating a Delta Quadrant Cardassian empire? No one else would be on board for that.
Get home faster by selling the Ocampa to the Kazon? Couldn't happen after Janeway destroyed the array.
Get home faster by meaning really mean to the people you meet? The only that works is if you enjoy being mean, so that the time seems to pass faster.
Have Chakotay's child? Not even Chakotay wanted that, Neelix sure wouldn't.
Unite the Maquis and Starfleet parts of the crew in anti-Cardassianism by engaging in pointless but menacing plots against everybody? That's basically the function of the character, but there was no reason for Seska to do this, except she was an eeeeevil Space Nazi, er, Cardassian.
If Seska had stayed on board after being exposed, there might have been a real Maquis/Starfleet conflict over what to do with the Cardassian spy. But I suppose that the Maquis slavering to imprison/maroon/murder her would have made the Maquis look bad, so that was out.