I don't get it.
Distilled and silver have been safe for a very long time, and suddenly its not, or its just for EK?
As I hadn't seen anyone describe this issue on another company's blocks.
I got a used nickel swiftech block which was used for almost a year using silver and distilled, and it doesn't show any signs or issues. Clean as a whistle.

Also just noting that for some, sending the block and getting it back on their own money, is going to cost as much as the block itself.
In that case I would prefer to get a new block from another company, check if my current full nickle one is clean, and sell it if it does. Same with my 580 block.