Narongsak explained that the divers had fixed rope lines along the passageway and distributed oxygen tanks along their route, allowing them to advance through the exceptionally narrow passageway unencumbered by bulky equipment. Other teams worked to pump out floodwater and divert groundwater, he said.
In such situations it's best to go with the simplest solution you know will work and people are trained for, instead of trying to get fancy and possibly endanger the whole undertaking (imagine a robot getting stuck somewhere and blocking the way for everyone...).
I don't know anything about that cave, but it's quite common for cave divers to remove their equipment (and put it in front of them) because a passage is so small that the diver and a gas tank won't fit at the same time. What's the chance of a robot doing the same?