Considering these three things:
1) From his remarks, the pilot was observing Charlie closely - seeing what he believed was traffic on that "runway".
2) Images were posted earlier in this thread of roughly what might be seen from the cockpit. Those images should have made the runway situation very clear to the pilot.
3) Before the go around was issued, the pilot had already overflown a quarter mile of runway.
I don't see an easy explanation for this. But here is my best guess:
On first siting of the runways, at long distance, the pilot mis-identified Charlie as 28R. He also saw traffic on that runway. From that point on, he was focused on the status of that traffic. In his mindset, it was more important to resolve the traffic issue that to further peruse the overall runway pattern. (Per a previous post, he wasn't looking for the guerrillas.)
At a certain point on his approach, he decided that the traffic might not resolve in time for his landing - so he informed the tower of the traffic - and was recleared for the landing.
He have had a rapidly improving view of the traffic of Charlie - so it is unlikely (or impossible) at that point that he would have resolved to land. Quite the contrary, he must have been very alarmed at the tower response. It probably indicated to him that they were completely unreliable.
By the time the other craft alerted the tower of the Charlie approach, 759 had no intention of landing and the go around was already in progress. But at that point, he still had a problem: he didn't not know what clearance the other traffic on "28R" (ie, Charlie) had received or would soon receive. So his close approach to the runway was likely intentional - for the purpose of keeping his avoidance options open and to see and be seen.