I don't particularly disagree. Although it's worth noting that people don't typically pick embedded languages because they're familiar with the embedded language per se, but instead because they (1) are easy to integrate, and (2) resemble the syntax/semantics of the embedding language. Rhai appears to satisfy both, so I can understand why someone would pick it.

(I don't have a dog in this fight; I'm not a user of either Lua or Rhai.)