"Why and how do Munger and Buffett “discount the future cash flows” at the 30-year U.S. Treasury Rate?"

From 25iq:

Buffett and Munger use several methods which are at odds with traditional financial theory. Here is one of those nontraditional approaches:Buffett: “We don’t discount the future cash flows at 9% or 10%; we use the U.S. treasury rate. We try to deal with things about which we are quite certain. You can’t compensate for risk by using a high discount rate.”There is no law of nature