Actually, Lowell does have value. Now, he won't get the job done by himself or as the centerpiece, but nobody has suggested that.
Texas is guaranteed one thing right now if they don't trade Tex. Two draft picks. If they trade him, the gain is the difference between what they get and the draft picks. With Lowell as a throw in (and competent player for the remainder of this year), the gain will be what they get and the draft picks. Scoff at the value of draft picks all you want, but the top prospects we keep talking about, Hughes, Buchholz, Bowden, Ellsbury, Chamberlain, Kennedy, etc were all 1/1s talent.