Obama argues that Guantanamo encourages terrorism
This is a smaller and more dubious version of a larger and certain argument by Robert Pape.
Pape argues that suicide terrorism is ALWAYS a function of a militarily weak power attacking a democratic country which is perceived to be occupying the former's land. (Religious differences-- often presumed to be primary or exclusive-- are only a SECONDARY cause, but can exacerbate the primary determinants.)
Obama is correct to be concerned about the feedback effects of our policy at Guantanamo. But it seems unlikely that our policy there will be perceived as strongly as our general foreign policy-- with its perception of occupation of Middle Eastern lands through the growth of military bases and the prevalence of troops (despite our promises) since the early 1990s.