The Vong lost their connection somehow. It is thought Sekot did it to them like the Exile did to himself, but I personally wonder if they didn't have the same thing happen to them that happened to the Rakata.
In anycase, Nihilus would not be able to eat one, but force lightning, or any force attack that strikes with energy is. We don't know how good Nihilus is though.
Personally, I don't know.
I'm just saying that it isn't going to be his strong-point. Also, a frontline genreal, like Mace, Hoth, Malak or Obi-wan is good, but the kind just sit on ships, although not horrible, aren't the greatest(Ackbar, for example). I know it sounds dumb to compare Ackbar to Nihilus, but you get my point.
It wasn't explicitly mentioned, but that is a strong suspicion. It does seem highly suspicious that Exile becomes a "wound" and then Traya suddenly "fishes" Nihilus from the depths of hell.
That along with some other issues that I'm sure Janus and Fishy have dissected give that theory some merit. I'm not going to make a call on it, but I will recognize it as being put out.