I hadn't considered the rocky surface
It would certainly make the location less practical and more dangerous, at least until they could get bulldozers up there. I'd also like to know not only the length and depth of the caves, but the height from the floor to the ceiling to understand the practicality of reinforcement. It's exciting though that there is an actual plan in the works within NASA to explore these lava tubes. I would think they would want to prioritize a mission right after Shackleton Crater.