This is not at all true. A client side exploit cannot stop a server script from running that is impossible. These checks also should not be done on the client and are easily and reliably done on the server. Metatables are useless for stopping exploits and you shouldn’t be implementing script protection like this because it has no effect. _G has nothing to do with scripts, it’s just a table that all scripts have access to. RayCasting has nothing to do with detecting teleportation either.
As for the question,
my article gives a some examples of preventing movement exploits from the server including stopping teleportation. How you should secure your game - A beginner guide for secure networking and developing anticheats - #43 by Hexcede
I would not recommend kicking or punishing players for teleporting either, but rather simply stopping this teleportation like I show in my examples.