What are they doing to Southdale?

They're chopping off the vertical brick lines, that's what. The final steps of deGruenizing the structure. This is the part they haven't smoothed out yet:

Those lines are iconic! Well, no, they're not, but they're part of the style. Here's the old Dayton's in St. Paul, by the same architect. He liked those lines.

I'll make some calls.
VotD Anthropologists may study this one for years; it is a rich vein of sociological information about early 21st century parenting, aggression amidst affluence, the ease with which children can be taught to feel entitled to anything and immune from judgment, the chilling effect of lawsuits on individual initiative, and the inability of people to hold their cameras correctly.
News reports say the combatants were gone by the time police got there. Smoking Gun says:
"Contributing" seems to understate the case.