But yes, the Red Ants have moved in. One of my housemates, who's one of those crazy surfer guys, regularly goes to De Ponte to abseil down from the roof (!!). He told me that 4 years ago, they only dared to get in wearing bullet proof vests. Now the scariest things in the building are the smells and the elevators - they don't stop properly, but oscillate up and down for a while but the doors have already opened...
I briefly considered to get one of those new apartments, but the areas around De Ponte are still rather rough. If I had the money, I'd follow what is described in your linked article: buy it as investment. I'm pretty sure that within 5 years time one'd make a large return.
I remember when even the cops wouldn't go into the Ponte, and I wondered if it was even going to be possible to clear it.
Regarding your roommate's passtime, I guess I need to be thankful that I have enough excitement in my life that I don't feel even the slightest need to jump off a building in Hillbrow in my spare time.