The fact that that person happened to be looking on a system downstream to this one, while also having the context needed to pin it back to xz in particular is the lucky part. The same attack in any of countless other places wouldn’t have gotten spotted the same way, or as quickly. That’s not to say diligence on Freund’s part wasn’t a big factor here, but it’s important to identify that luck was a big factor.
The fact that that person happened to be looking on a system downstream to this one, while also having the context needed to pin it back to xz in particular is the lucky part. The same attack in any of countless other places wouldn’t have gotten spotted the same way, or as quickly. That’s not to say diligence on Freund’s part wasn’t a big factor here, but it’s important to identify that luck was a big factor.