Zamboni nailed it. I'm sure that Munger, Tolles & Olson would have preferred that WEB not publish a number at or below which BRK might repurchase shares. But given that WEB has published a number (now increased from the original number), it has to be based on book value at the most recently publicly disclosed book value, not some book value that WEB has calculated using undisclosed, insider info.

We also shouldn't get too excited about the "floor" created by his repurchase number. That floor won't support a lot of the weight in the event of a strong market downdraft. WEB is not obligating the company to buy at or below that price. He is simply saying that BRK would consider buying at or below the publicly released multiple of book value. Current daily trading volumes make the potential impact on the value of such buys minimal at best.

We are approaching a time, in my opinion, when the market will quit being happy due to the discoveries of rapid interest rate increases, earnings declines due to government and private sector spending reductions and the impact of tax increases (ignore the short term "fiscal cliff" ruse that the media and the politicians are hyping in order to respectively sell advertising or buy votes). When that happens, 1.2 times book value might be based on a book value of $100,000/share and WEB might find much better values for BRK cash than BRK trading at $95,000/share. Not a guaranteed future, but definitely not a zero probability either.