Unlike the NY-SAFE act, it was a public referendum and the will of the voters in Washington.
It speaks more of the (stupid)voters in Washington State than it does anything else. Protesting a ballot initiative seems odd, but take it to court, (and judge shop) like the sodomites did with fag marriage.
It is a very dangerous tactic.
It depended on three things:
1. Massive saturation of deceptive messaging to low information voters, done with overwhelming money supples, perhaps 8-10 to one.
2. Complicity on the part of the old media to exclude contrary messages.
3. Well done get out the vote and targeted messaging to low information voters, identified with google analytics type information.
It might have been countered with a strong effort from the second amendment side. But they could not overcome the monetary and media advantage of the Bloomberg machine on this.
They simply could not get their message out.