My guess would be that the pet battle code and anything else they're handling via lua is done in an entirely seperate lua state with a much lower-level set of API functions at hand to them, so really exporting those files would be quite pointless. We'd be able to see what they're doing to a point, and learn how it works internally, but we wouldn't be able to really replicate it in our own addons simply because we don't have the full power that they do.
In addition it's all probably compiled into bytecode and embedded somewhere, so they'd either need to not do that or to decompile it during extraction, both of which I'm sure they're not interested in doing (time/effort for the eventual reward aren't worth it).
As for nameplates, I'm sure they're entirely in C. Call it a hunch
