I'm not an expert programmer, but from what I have learned over the years is that the scripting language does not matter that much, since it is usually not performance relevant stuff and that the performance relevant stuff should be in C++ anyway, which beats any scripting language in performance. Others even use things like blueprints aka visual scripting and they are the worst regarding performance, but it does not matter since it is not that performance relevant and modern computers are fast enough.
It is mostly just a belief war and most people fighting it have no clue about anything, if you want to make a point, make a demo and measure the results, so you can present a definitive proof, everything else is probably not constructive.
I saw implementations of Lua in Torque and then you had a scripting folder with Torquescript and one with Lua, making everything even worse. I also saw games written totally in Lua and they had horrible performance because of that. To make it short, I have not seen any evidence yet that would convince me that another scripting language would make sense to use. Sure the engine is open source, so you can do what you want, but please do not break the old stuff, there are people using it, that's my biggest concern.