tbh I think the tank commander is the true hero.

While many people died later that day, why didn't he just run this guy over? why did he opened the hatch to talk to the guy?

After the hatch opened and they communicated, you noticed how the guy (in white) become a bit softer, his action/movement become less rigid.

I believe he is the commander of this line of tanks because how the rest of the tanks not overtake him or just gun the man down (you can hear machine gun fires from a distance)

One of my close friend from China was there, she is a university professor in Beijing (luckily she was able to get out of China). She told me later that the tank guy or the people came in during the day was pretty much the National Guard of Beijing, who could not bear the command of harm the students because they could be their neighbors or even their friends' kid. But later that day the Army from a neighbor province arrived and started the massacre.

I don't know how much truth that story hold, but I do think about it every time I see how much restriction the tank driver is showing in the tankman picture/video.