Why was the “Giant of Kandahar” there? Why was he alone? What, if anything, was he guarding?

He was left behind in an earlier foray into the region for surveillance purposes and to recover some artifacts of importance to clouding their history. As you know, there have been many, many, artifacts of the early Anunnaki presence destroyed, especially during the wars in Iraq and Afghanistan. And so there have been many forays done to destroy historical links to important events that took place and this they like to do themselves because they do not trust anyone else to take care of it effectively. This particular individual was separated from his group and was simply left behind and was not following orders and so was in effect punished by this means. There are a number of lower-level Anunnaki in terms of the hierarchy, some of whom have much more limited capabilities, particularly with respect to intuitive reach, and they may well have difficulty communicating with their brethren and can fall into difficulty if they become isolated and forgotten in this way.