Jira was axed late in the project. We kept waiting for photo reference of Jira but never got it. Add to that the fact that Jabba's Porter (which is the OTHER end of the Paddy Frog quest) had a dialogue tree that had a series of bugs, it was easier to amputate both than spend time to de-bug the Porter and come up with some half-assed model for Jira. The whole side-quest didn't give much as a reward, I believe it might have been a rocket launcher or something else unique to the level. However, both characters' lines were left in the dialogue file for some reason, and their .wav files might still even be on the CD.
BTW, I was the one responsible for the bugs in the Jabba Porter dialogue...I set it up in a way similar to Watto's Flunky and some of the speaking characters on the Garden level, where you could leave the conversation any time, yet come back and pick it up where you left off. However, for some reason he kept forgetting who you were - I think his active/inactive distance was set too low.
There isn't an invincibility code. We had one for debugging purposes, but our project leaders decided that they didn't want that code in the final build.