Loot change lock while in combat?

Since i played from retail wotlk and even tbc, ninjalooting has always been an issue, even moreso on private servers where it doesn't have the same impact when accounts are banned.

While on retail they did implement personal loot, I imagine it would take quite a bit of coding to implement same on the current client version, but making players unable to change to masterloot while in combat would at least reduce the occurrence of ninja. I'm sure some would be able to bypass this by hearthstoning etc but it will make it harder for them, and would require much much less coding than personal loot implementation.

What do you guys think?

What if the raid is meant to have ML, but the RL forgot to put it on?
What then when few players thinks it's okay to roll gear because "they were allowed to" while also breaking the rules?
What if there's a combat bug that prevents the RL to put ML?
What if somebody pulls before RL had a chance to put ML on?
What if RL gave ML to person who logged their main to do a hard encounter, making ML offline?
What if ML disconnects in middle of the fight?

Did you think this through from different perspectives, or where you only focusing on evil PUG leaders?

Ninja looting is never an issue if you do GDKPs.