Sorry, but Cashill is wrong. Here, look at the sentence without the dependent claue:
"The belief that moribund institutions . . . keep SAM’s energies alive.,,,"
That is grammatically correct. ' The verb 'keep' agrees with its noun 'institutions'. If the quote were extended, I suspect we would see the verb that agrees with 'belief' in the complete sentence. Or not.
I am no Grammar scholar, but I do believe that Cashill is right on this one. The subject is “the belief” - hence the verb needs to be “keeps”. The rest of that “moribund” phrase modifies the subject.
The point is not about this one bit of grammar but more about expert literary style, of which Obama has none (based on his own few works prior to moving to the ‘Hood).
All that matters now is that the Anointed One and his Bride are in POWER and about to go very shrill on their adoring fans.
“The belief that moribund institutions, rather than individuals are at the root of the problem, keep SAM’s energies alive.”
The noun “institutions” goes with the verb “are,” while the noun “belief” ought to go with the verb “keeps”. I think we all agree on that. Obama made a further mistake in punctuation, the correction of which, I think, would greatly aid in clarifying the sentence’s meaning. The comma after “institutions” should be paired with another after “individuals,” thereby setting off the phrase “rather than individuals” from the body of the sentence. As it stands, with a lonely comma after “institutions,” one wonders what the point of pausing is.