The handholding occurs between friends as a general rule. Turks hold hands also.
The point is, it is NOT a gesture of subservience, which the salaam most definitely is.
Perhaps you have spent more time in Saudi Arabia, Egypt, Bahrain, the UAE and Dubai than I have. And while there are some of their customs that I follow while I am there, we do not hold hands.
Moreover, the picture in question was taken in Texas, not Saudi Arabia.