Please pardon my ignorance regarding a lot of these matters. But a quick question... suppose Symantec valued their IP portfolio at, say, $50 billion (just picking a number out of thin air) for purposes of some required SEC filing or what-not. Investors, relying on this information, increase their valuation of Symantec's stock, and Symantec benefits. Now, when Symantec sells its portfolio to Irish subsidiary, it sells it for only $40 billion, getting the benefit of the lower valuation (less taxes relating to the sale, etc.) It seems that there's a basic principle that if you take a position as to the value of an asset, you should take the good with the bad.
If this is the situation, then I don't think it's simply sour grapes on the part of the IRS. Then again, if this isn't the situation, it might be.