Hmm, well that is a good point, although this only could help explain the state of nuclear research in Muslim countries, not other areas of research.
I looked at the list of Iraqi academics killed during the U.S.-coalition occupation, published by Pakistan Daily. But is there evidence the U.S. went around deliberately assassinating Iraqi academics? There are many attacks and assassinations that occurred in Iraq which we know were done by militant Sunni or Shi'a groups there, so why couldn't they be responsible for these assassinations as well? The academics in the list could have been among many thousands who were killed by a fanatical suicide bomber while
leaving a mosque, and many other similar attacks and killings, for example (in these particular attacks al-Zarqawi claimed responsibility). Many prominent Iraqis have been assassinated because they worked for the Iraqi government or cooperated with the coalition forces.
Personally, I do not see why Saudi Arabia could not make outstanding contributions to science. The Saudis have the wealth and security and the goodwill of Western governments. I could be wrong, but the examples of Saudi science I have seen are beholden to the religion of Islam in some way instead of just doing science (e.g. a textbook about how the human embryo is accurately described by the Qu'ran, or award-winning student research on the medicinal properties of nano-particles and camel urine, as predicted by the hadith). I've also seen the Saudi government trying to attract U.S. science students to go to Saudi Arabia, I don't think these efforts are very successful, on the other hand U.S. universities have too many international applicants and a relative shortage of American scientists.