His generals are not allowed anywhere near him and all go through very thorough screening before they are even allowed in the same room. It would take a lot of planning to take him out from the inside although I suspect many would want to.
There was an interesting interview on GB News this morning with a Ukrainian villager whose village was 'attacked'. There were burnt out tanks in the background and he was saying the Russian troops captured were happy as they only came into the village looking for food. They were telling villagers they were initially told it was only an exercise.