Good catch as this hadn't been published elsewhere.

So Alitalia isn't involved

I assume that NW is subsumed into DL for this purpose.

Three carriers allow them for a fare below Y.

Their commincation is quite bad, and to be frank this program isn;t too impressive. I suppose its a sap to the economy, allowing those travelling on business for companies with economy only restrictions to sit up in Business class, as I cannot imagine anyone doing this for leisure (especially when many companies discount rates are listed as Y fares).