the only way to pay proper respect to all religions is to not allow any one of them to dominate. that requires an ironic restriction on posts that are either obviously for overtly religious purposes, or which any reasonable person could interpret as being for the purpose of promoting a particular religion, method of worship, or point of view.
the problem - for lack of a better word - was never the prayer requests themselves. the problem was the responses.
they created a loophole that zealots used to exploit for the purposes of evangelizing, proseletizing, and imposing their points of view on the general membership.
the decision to permit prayer requests in PDAs was a collective compromise.