The part you're referencing is Theo speculating about the next bug. He suspects fixing it requires flushing a cash line but he doesn't know which one (because he doesn't know where the bug is) so he proposes flushing all of them until the bug is published and then removing the flushes that aren't necessary.
He then mentions the last serious OpenSSH bug. Instead of publishing a fix for the bug (and thus disclosing the bug) they decided to publish a patch that moved a bunch of code around and just happened to also make the buggy code unreachable. Then they told everybody to upgrade and once that happened they could safely disclose the bug and publish a fix for it. No embargo necessary and everybody got the fix at the same time. (I assume that's why he brought it up.)