I can't find the evaluation paper they cited in the second linked paper, but it looks like it's using Javascript because they wanted a COTS script engine (as op

I can't find the evaluation paper they cited in the second linked paper, but it looks like it's using Javascript because they wanted a COTS script engine (as opposed to running compiled code) that was compatible with VxWorks, and the particular Javascript engine they selected (ScriptEase) was presumably the best option they found back in 2003. I'm not really sure what all options they would have had in 2003 though.