Been following this for bit.
Do have any old HP/KS test gear personally, no. So I have not gotten a letter.
I suspect something like this happened. Gear was used a high controlled area.
The rules are like a RAID Roach Motel, they check-in and never check-out. Gear, papers, things can go in. Nothing comes out without being shredded or completely destroyed. Even when it is ground down, it gets mixed with more metal from non highly controlled areas. Then that whole bit is melted down and then sold as scrape metal.
Someone goofed up and removed the gear and didn't follow the right process. It was sent to DMRO and they sold it in a large lot. That company sorted things out and tossed real junk, and sold the rest on eBay.
Now someone at the facility realized the mistake. Where is serial number XYZ, what pile of metal dust is it? Think, think, don't want to tell the new owner what is up. Let's see if we can pay KS to "swap" them units and we get back they one that should have been melted down, and we can close that out of the inventory system once we have it back and correctly scrape it.
Ebay seller is helping by giving names of people they sold the things to, KS is helping and getting paid to help recover the gear. Neither makes the rules, they are just doing their part to get the gear back.
HP/KS has delt with this type of thing before. If you have gear on a maint contract in a special area, there is a standard up charge for them not getting back defective parts to refurbish.