The planning was excellent.
They can sue the state and all responsible individuals for seizing the tithing money and almost certainly will.
You can sue anyone for anything. Doesn't mean they will win.
The Religious Liberty and Charitable Donation Protection Act applies only to bankruptcy cases, and then only if the giving is less than 15% of the gross income. And Gross Income might not mean what you might think it would mean. See, for a quick overview of Sec. 548(a)(1)(B), Wadsworth v. Word of Life Christian Center (In re McGough, 2013 737 F.3d 1269 (10th Cir. 2013)
If these folks wanted to give the money to the church, the best course of action would have been to drop it in the plate in cash, not holding it in a bank account. Show me copies of the signature cards for the accounts, and I'll let you know whether they were subject to garnishment.
As to the alleged shock of the account holders - Oregon law provides that the bank give notice and an opportunity to contest a garnishment. Think it is somewhere around O.R.S. 18.785.