It does kind of make you wonder - what is the data that is worth backing up in a really futureproof manner? If we keep our tech level, we’re probably not going to need to relearn how to make semiconductors. If we do not, we probably have bigger concerns than what a user with the nick rebuilder said on a nerdy forum in the year 2021.
A futureproof encoding would have to be something like images at a scale visible to the naked eye engraved in a substance that cannot be corroded or destroyed. Stainless steel is probably fine for the material, but you run into limits on the amount of space (and steel) you're willing to devote to the project. And most information just can't be represented pictorially anyway, so the theoretical possibility of futureproof storage isn't even there.
Stainless steel still corrodes, and even 316 can't even be used for many marine applications because of the salt water corroding it. Maybe fancier alloys are OK but for 1000s of years, it might pay to use something more history-tested.