Living in Wilayah Narathiwat, I spoke to my friends here, including imams.
We believe this man was mentally ill, simply for the fact that in Islam it is forbidden to commit suicide:
"And do not kill yourselves,” says the Holy Qur'an (nor kill one another).
“Allah is, without a doubt, most merciful to you” (Surah al‐Nisa, 4:29).
And Allah knows best.
أمين