Grash-Varrag-Arushat doesn't react to the player because his NPCTYPE gets reset

[OrcPriestPsychologist]

Describe the bug Sometimes Grash-Varrag-Arushat (the last undead orc shaman, orc_priest_5) pretends to be a tree. Doesn't react to the player. Even when the player attacks him. Like on this video https://youtu.be/o9-Gixamn7w?t=1266

The reason is that his npctype is NPCTYPE_FRIEND instead of NPCTYPE_MAIN.

Manually changing npctype with the console restores the functioning of the shaman (edit abilities -> npctype = 1)

Grash-Varrag-Arushat's initial npctype is NPCTYPE_FRIEND. It's done this way to allow the player without charged Uriziel safely attack the shaman 3 times with a regular weapon and find out that regular weapons don't work here. And get a portion of EXP and a record in the journal. Then a script gets triggered and changes npctype to NPCTYPE_MAIN. After the change the shaman stops being a friend and starts to attack the player. Another script with a similar effect can be triggered by having charged Uriziel or Uriziel's rune.

But if the player leaves the temple and then returns the shaman's npctype gets reset to the initial value NPCTYPE_FRIEND. The same happens if the player just saves and then loads the game.

The scripts changing npctype to NPCTYPE_MAIN won't work second time. So the shaman stucks with NPCTYPE_FRIEND.

Expected behavior Grash-Varrag-Arushat doesn't act as a tree. And doesn't have his 'npctype` reset.

Steps to reproduce the issue

1. Start a new game
2. Get any weapon
3. Enter the Temple of the Sleeper.
4. Go to Grash-Varrag-Arushat.
5. Make him attack the player by hitting him 3 times with a regualr weapon and not having charged Uriziel (mythrilklinge02) or Uriziel's Wave of Death (urizielrune) in the inventory. Or by approaching him having one of these 2 items.
6. Run.
7. Save/load the game. Or exit/enter the temple.
8. The shaman doesn't react to the player.

Additional context The player is supposed to leave the temple after getting the uncharged Uriziel. Reentering the temple triggers the bug. So the bug affects everybody who decides to go deeper after getting the strange sword and meets Grash-Varrag-Arushat. And doesn't affect people who delay the meeting.