According to Wikipedia, while a market for old, low-background steel was real phenomenon for a few decades, that's pretty much over.

World anthropogenic background radiation ... began to fall in 1963 ... and by 2008 it had decreased to only 0.005 mSv/yr above natural levels.[9] This has made special low-background steel no longer necessary for most radiation-sensitive uses, as new steel now has a low enough radioactive signature.

So you may consider your friend's estate-sale theory in light of that time-line.

but it carries some weight

Did you know about !dadjokes@lemmy.world?