You have no idea what 90% of their users are using. A lot of them aren't using LLVM or GCC. I'm pretty sure Roblox and WoW, for example, aren't normally compiled with LLVM or GCC. Whether those two games account for 99% of Lua's users or 0.001% depends on how you count, but no matter how you count, you have no idea.

Embedders of Lua are not equidistributed across platforms with the general population of programmers or with user-exposed general-purpose computers. Not even close. One of the selling points of Lua is how easy it is to run on a toaster or potato, so disproportionately many ports of Lua are in fact running on toasters and potatoes.