Just curious to know, did he de-convert himself back to Chinese Religion? 

I'm adopted by Guanyin too and I abstain from beef. 

Tales of the mysterious Toa Payoh God Tree

It is believed to be more than 100 years old. It was approximately six storeys tall.

The tree collapsed on Sept. 11 2013 at around 2 p.m. during a storm.

Urban legend has it that when work began to develop Toa Payoh New Town in 1965, the bulldozers sent to flatten the area allegedly malfunctioned when they approached the tree.
The history

The bulldozers could only move in reverse, but not forward towards the tree.

Religious leaders offered prayers to the tree but it “refused” to budge.

The authorities then decided to leave the tree alone.

Residents believe the government took the tree into consideration when planning Toa Payoh town’s layout.

'Kept ghosts' can be divided into three categories.

The first category are those who are fugitives from the spiritual law, who are trying to escape their final judgement - they find refuge with those who are willing to keep and provide for them, in exchange for favours.

The second category are those who are detained against their will by black magic practitioners and forced to serve their captors, cruelly prevented from crossing over into the next world.

The third category are authorised by a deity or deities to be kept by certain individuals (e.g. priests, monks, spiritual masters) and perform good deeds in their service as a form of penance or spiritual cultivation.

People who keep ghosts belonging to category #1 are guilty of harbouring criminals on the run.

People who keep ghosts belonging to category #2 are guilty of unlawful detention/slavery.

Severe penalties apply to such offenders, so avoid such activities like the plague.

Why does a ghost need to possess a person to reincarnate?

I'm quite mystified here - as mystified as Yeeck is.

Possessing a person does not serve to facilitate reincarnation for a ghost, let alone hasten it.

What sort of logic is this?

There isn't very much serious discussion going on in that thread, is there? 

Indeed; they're fairly obscure.

The only temple I'm aware of where they're worshiped is in Kepong (KL).