This behavior of unplugging the destination of the DDoS is common with smaller hosts. They don't have the capital to spend on expensive mitigation devices. There are times when these attacks affect their entire network (bad design), so their quick and fast solution is to null route you at their cores.
The issue isn't unplugging, I don't think anybody here thinks that it is unreasonable if they were to do this. The issue is that they kept the site unplugged for good because a single DDoS attack. My analysis based on the official response is that they used this incident as an excuse to drop the site because it was too much of a hassle to deal with the takedown notices.
"Smaller hosts" like this are imho companies that sell a service they are fundamentally unable of actually maintaining. And they are usually not very transparent about it.
