When I first thought of the "countdown to war mechanic," that's actually specifically what I wanted addressed. Obviously it helps protect against blindsides/suicides which is nice, but a small tag or suicider bunch with no intention of being able to win should have the damage they do massively mitigated by the larger tag, and having the larger tag involved in the first strike should make a declaration of victory eminent.

While it doesn't eliminate the ability to grief completely, it should be rather easy to win those types of war very quickly, and gain a sum of money for damage caused. It's more of a nuisance than a set ruiner.