Straw is abundant in Lesotho, so it is very smart for them to use this material to build their nests. Because it can be very windy here, a nest woven into the tree is more stable than one just sitting on a branch.
Aside from strong winds and rain that can destroy their nests, I don't think there are a lot of predators here that can harm these birds. There are almost no large mammals besides those kept for food, such as cows and goats.
