Can Sion die?

I am currently trying to find a place for Sion on my tier list, and I am wondering if I should even include his immortality in his ranking.

Besides convincing him to die, is there another way to legitametely kill the dude?

At the very least, anyone capable of using Wall of Light or Sever Force should be able to defeat Sion. Cut him off from his source of immortality, and he dies. Other than that, I don't believe he can be killed through more conventional means.

He literally died in KOTOR 2.

Once his willpower runs out he dies. He doesn't have infinite willpower therefore he isn't immortal.

Throw a ysalamiri on him and he'll die instantly

Sion can die if you can erode his will, but that's more about convincing him that he's never going to compare to Revan or the Exile than typical dun moch.

I mean his immortality isn't a NLF, just do something bigger than he has already withstood, he hasn't shown the capacity of surviving things such as being flung into a star or immediate disintegration.

He's tanked a point-blank enraged Force blast from Nihilus, so clearly he's got an insane level of durability.

One method is/was by eroding his will...

That could be accomplished through careful application of Dun Möch and/or Mind Control (assuming incredible proficiency in Telepathy).

Only by lessening his will or by cutting him off from the dark side (sever/WOL)