For me, when I click the link in TFA, that message is shown as the last message in the tree, with no children.

I just tried again, still didn't show any children. Then I did a force-refresh. Now it shows them ...

So due to past terrible performance of lkml.org, it had aggressive long-term caching. So since I happened to see this message a couple days ago, it wasn't showing a newer version of the reply tree for me, I only found them in the top-messages list on the lkml.org main page.