A interesting article from the New Yorker gives a potted history of the topic which is consistent with what I have heard, and our experience (subject pool of 1!), although I haven't accessed the primary sources.

http://www.newyorker.com/tech/elements/youngest-kid-smartest-kid

The rationalization is, while being older in a sports cohort conveys advantages, the same does not necessarily true in academics. Certainly from what we have seen, one of the big advantages of acceleration is that our DD has to work harder to be near the top of the class. There is no advantage to being first in the class if you didn't learn anything new that year. Interestingly one of DDs friends doesn't like being accelerated because being first is so very important to her where DD cares more about learning new things.

So the answer would appear to be that there is research to support the idea that red shirting does not convey an academic advantage, and may in fact do the opposite.

In a related argument , there is research to support not repeating students if they do poorly, as the repitition can do more harm than good.

http://www.du.edu/marsicoinstitute/policy/Does_Retention_Help_Struggling_Learners_No.pdf