It's really simple:
"The problem with that is that he is already supposed to be dead." - Nope, that was the Ba'ul lie.
"Saru reached the end of the Kelpien life cycle, and kept going." - Nope, the Kelpien life cycle naturally goes beyond Vahar'ai, which was never the end of their life cyle.
Saru was supposed to be ritually murdered before he thought he would die of natural causes painfully.
He wasn't.
That Baul lie is apparant reality.
They have been lied to about their life cycle.
We are regurgitating the same facts.
What Saru believed was his life cycle was his life cycle. It's what all the biology text books at his high school told him.
Until he found out it was a lie, he thought it was true, so it was true until proved otherwise.
He reached what he thought was the end of his life cycle and asked to be murdered.
He should have been dead, because Michael should have killed him.
Was it Michael?
Michael, or who ever didn't use that pretty knife on him, so he didn't die from a knife. Not natural causes. From a knife.
He didn't die of natural causes and he didn't die of knife.
The first Kelpien in over 700 hundred years to live past puberty.
The life cycle is redefined.
New information
Maybe no one else should unnessaryily murder their relatives either moving forward.