It's interesting that you are using LuaJ in your clojure app! I thought Lua was mostly used for scripting games, so I'm curious now: What is the benefit of using it within your closure app? What do you use it for?
> What is the benefit of using it within your closure app?
The benefit is probably it not being Clojure. While objectively not any better, more people are familiar with the non-prefix syntax and imperative semantics. If you intend the scripts to be written by some 3rd party, trying to convince them that Lisps are great is a waste of time. I mean, they are great - but there are many programmers (a majority, even) who don't care or can't appreciate it, and it gets even worse if you consider other professionals in the field.
If not for this, and if you don't need any particular feature the other language provides (in Lua it would be either sandboxing or coroutines, I think), then Clojure is perfectly capable of being used for scripting. Even more so than most languages; for example, simple syntax and macros (and the resulting ease of making DSLs) are desirable properties in a scripting language.
It's used in a rule engine for cases where the user needs an escape hatch to express super context specific rules we do not provide matchers for out of the box.