Currently, ZOS apparently has no mechanism in place to assist military personnel (or military affiliated personnel) who are on deployment and miss limited-time items in the crown store.
It is my opinion that ZOS should reward and not penalize military personnel, and if they are deployed (perhaps with proof provided) allow them to purchase limited-time items after-the-fact.
For example, I am a civilian engineer who deploys with naval groups (usually for 2-4 months at a time). For any special items released in the crown store while I am deployed, I am simply out-of-luck. I was on deployment when the Black Senche was released. I wrote in to ask if there were any options, and while "Helping you is our passion!" was at the top of every reply from ZOS, in the end, the answer was (paraphrased) "Sorry. That was a limited time item and is no longer available." So in the end, I am away from ESO, supporting the personnel who defend our country, and I (like the other military personnal who also missed the limited time window) are still out-of-luck.
I do not feel I am asking for anything "special". I am a paying ESO Plus member. I am a long-time fan of TES series (I have played every game of the series). I also feel there is a legitimate reason for accomodation. As it is against ZOS/ESO policy to have someone else log into your account for you, and because there is no "announcement as to special, limited-time items - and even if there were, there'd me no way I could log in to ESO while on a ship, deployed on the far side of the world - which loops us back to the issue of, "We're just SOL".
tl;dr - Military personnel who are deployed when there are limited-time CS items are out-of-luck. There is apparently no mechanism to accommodate them after-the-fact.
ZOS, please, please allow for accommodation of military affiliated personnel. Most, I think, would be more than willing to provide copies (or redacted copies) of their orders as proof of deployment. Put another way, I am willing to spend my money on an item that I had no other means to obtain (without violating the "rules").