In a word: arseholes. Alas, such patents are far too common these days; granting and refusal of same has become pretty arbritrary in recent years, and seems to depend more upon the lawyers than the science.

Apropos of stupid patents, one of my favourites of the last n years was reported by the New Scientist late in 1994 (I think it was a November issue, but i'm too lazy to check). In simple terms, a company which produced diapers filed a patent for "synthetic faeces". Apparently their staff had reservations about working with the real thing when testing their products, so a substitute with similar physical properties was, um, excreted by R&D...