Let's look at it this way. 2.1 is CTR whereas 2.0 is RTC. This applies to backports. However, the Review for most backports is "already done" within the 2.1 CTR cycle. If the original has been in 2.1 for a "significant" amount of time, it implies review. So the required review for that backport in 2.0 is pretty much mostly done. In other words, the R for 2.0 backports assumes that the CTR process in 2.1 is actually being done.
This, I feel, should allow for some measurable leniency regarding backports in 2.0.