This is the response I received from AirBnB:
"Sorry to hear the window to leave a review has expired for you. It closes at local checkout time of the host on the 14th day from checkout, at no time is it advertised as the end of your local day. Regretfully, it is not possible to reopen this window once closed.
https://www.airbnb.com/help/article/995/
As the link above shows, AirBnB has become quite stringent on this as a matter of policy. You can read more about the rationale behind that policy here:
http://blog.airbnb.com/building-trust-new-review-system/
You can, however, offer to write the host a reference if he or she will extend the invitation to you. It will function much like a review and be visible on the host's profile page. Details on that here:
https://www.airbnb.com/help/article/173
Just message the host to explain via your Inbox.
Hope that gives you a viable option to pursue!"
I tend to agree more with the OP. I think AirBnB is being overly restrictive. I like the idea of holding reviews until both are able to read them at the same time, so that reviews are less biased based on what the other person said. However, I think everyone is different and some people are able to belch out words right away on their smart phone while they are traveling, while others might need a little more time to construct a nice response and want to take the time to do so.
This was the case for me. I knew in the back of my mind that it was due in 2 weeks, but I had tight travel plans that did not offer me sufficient time. When I returned home I started leaving a review and actually SAVED it in the system. However, when I returned to complete the review today the 14 days had just expired today and my saved review was deleted from the system. I wanted to leave a review in both English and Spanish, so that required me more time to think about what I was going to say since Spanish is not my first language.
In regard to AirBnB's reasoning for the policy. Who care's if 90% of people respond in two weeks? Last time I checked we're humans, not robots. Stopping using arbitrary data to make arbitrary decisions. I'm positive that AirBnB probably saves some money by restricting the deadline so that they don't have as much data to store on their data base (cloud). And they're moving more toward automation to save on costs, at the expense of their customers. Automation is not good for customer interaction and review processes.
Also, If someone's not going to respond, they're not going to respond regardless of whether it's 14 days or 5 months. Too long is relative. It may be too long or too short for you, but not for others.
As a potential solution that makes both sides happy, why doesn't AirBnB send a message asking if you want to extend the review period? Or add a button asking if you want to extend the review period on their webpage? Then you could click on the button to extend if you know that you want to review and the deadline is quickly approaching (and it's easier than having to write a review right that instant). People that never intended to leave a review would never click the button or ask for an extension so the 14 day window would run out like normal. Instead they've put the impetus on their customers to fill out references instead of just letting us extend the review time. AirBnB's review process is not well thought out currently and has aggravated me enough that I'm less likely to use them in the future for my travel needs.