Excluding that ,the hotel loses it's magic if the master dies.

I don't recall that they ever said that Asterion is not allowed to make a plan to kill the master of the realm.

For example: what if Asterion poisons the master ?,or what if Asterion changes the structure of the labyrinth  to booby trap the master ?

Does the master's order have to be of earshot to be followed by Asterion or does it just implement itself if the master orders  it to be?

the "magic" of the hotel does not come from the master. the realm was designed by the gods to constrict and punish asterion and other potential prisoners. even if he wanted to rebel, the contracts would prevent him from taking action against the master. besides, even if he was able to, it wouldn't  anything, the master is but a conduit to exact the realms purporse, which is fully capable of bringing harm to asterion without any master being present. in fact, the master may be one of the few protections asterion can have, as he was able to persuade previous masters to make the hotel and that protects him from the automated attacks the valley does to him.