As to the specifics of his suggestion, namely that the putter be restricted to a length no longer than the shortest club in the bag (generally the highest lofted wedge), it's a delightfully practical albeit half-baked attempt at proposing a rule that technically doesn't ban anchoring the putter but in large effect does. (I suppose one could choose to putt with a low-lofted hybrid jammed in your belly button, but at that point one could argue your game on the greens might be better served by some advanced pharmaceuticals.)
While practical and diplomatic, Tiger's idea is hardly original to him. Peter Dawson, the head of the Royal & Ancient Golf Club of St. Andrews who once suggested that a solution for distance was to ban the tee, juts his chin out just a little farther in characteristic disgust when the subject of belly putters is brought up. Insiders know the R&A has not been particularly thrilled with the long and belly putter for a long time before Webb Simpson and Keegan Bradley were getting paid to play golf. While others have proposed a limit on the length of the putter tied to the length of the driver minus a certain number (say nine inches), there's little doubt that whatever geometric theorem you invoke, the Tiger belly ban is just a politically demure way of getting around what's really distasteful, namely anchoring the putter to something other than your hands.
Arnold Palmer said in an interview on the Golf Channel in October the long and belly putter should be banned. Also on the Golf Channel, Brandel Chamblee has made the case intelligently that the belly putter could be Exhibit A in the case for bifurcation, that average golfers should be allowed to use almost anything on the putting green, but elite players should be restricted to conventional-length putters.