I don't understand why you have such a fixation on the sniper. With this change, you are castrating sniper play by making it too easy to countersnipe. And this is without mentioning the ramifications it will have with abilities like strafing run, bike/jeep drive by etc.
The problem, as I see it, is when one player gets the upper hand with regards to sniper superiority. When he has more than one and his opponent as the same time is forced to counter them with a sniper of his own (a grenspamming WM player vs US sniperspam, a fuel-starved/vehicle-countered US player who needs the sniper as anti infantry but is up against sniper spam, etc.). A reason to include the sniper in an early WM build was to already have prepared for eventual US snipers.
The above situations get fixed with the negative zeal effect, which helps a lone sniper when he is up against many. It will increase his chances of evening out the sniping field. And if he gets the countersnipe due to the negative zeal, there is still room for the spamming player to counterplay; after all, he still has a sniper of his own to make countersnipes with. For me, this is enough to alleviate any problems there were with sniper wars.
Think back to how sniper wars actually played out on high levels. Here, the game evolved around not necessarily getting the countersnipe, but instead of killing more troops with your sniper than his. This meant that it became a dance of death, trying to rack up as many kills as possible without being countersniped, using screening troops, los, range... It was micro intensive and rewarded active play.
With this change, we will instead have one player wait for his opponent to have the guts and courage to actually USE his unit, only for the passive player to be rewarded with a guaranteed hit...
I have to ask: Why this fixation on snipers, making them seem like a big problem that requires a redesign of the game mechanics? I can understand wanting to solve the problems of sniperspam... but instead you make such drastic changes that affect snipers in their entirety. Why make such a drastic change that, to me, reeks of wanting to "balance" the game in favor of your own playstyles?
So you have a problem with 100% accuracy for moving snipers or the 2 shot requirement on retreat? Or both?
The major issue is in the randomness of countersnipes, most noticeably the following issue: you bait his sniper to shot preparing a countersnipe but it misses, you retreat your sniper but his other sniper kills it on retreat. This situation only encourages to have more snipers because the more you have the better the chance to get a Sniper kill.
A compromise between these 2 perspectives can be to restore 50% moving accuracy but have 100% accuracy on retreat (heroic_critical), but maybe raise the number of shot needed to kill above 2.