> the above comment when using the word implication my intent was "a conclusion that can be drawn despite not being explicitly stated".
Yes, that is the same definition. But it is an error to draw that conclusion in question because it requires unsupported assumptions. That's why it's not implied in the original statement.
> The conclusion that can be drawn, based on the fact that the writer specified that date, is that later dates did not qualify for the same statement, because the conditions were not sufficient.
No, the later dates did not qualify because the knowledge is insufficient, or if you allow that the knowledge was an implicit part of the statement, it's not longer a binary proposition . If there are two true propositions that must be true for the original statement (we were insecure, and we know we were insecure), there are multiple alternatives. The problem is you are assuming a single one of the possible alternatives is implied, when it's not.
For example, I can say "up to this point in life, I haven't committed a felony." That does not imply I plan to commit a felony by itself. With additional context, it may or may not. I could just as easily follow that statement with "I don't see that changing any time soon" as with "I'm not sure if it's likely I'll still be able to say that next year." That additional context combined with the original statement carries the implication. In this case, people are assuming it's along the lines of one of those followups, when there is really no disambiguating context. Assuming one or the other is a problem of the person interpreting the statement, and in my opinion the root cause of quite a few arguments as a result of misunderstanding, which is why I called it out in the first place.
> That is to say, that they were not insecure enough for the writer to include in his comment.
Or they decided for whatever reasons they did not want to mention it. For example, to simplify the message and call attention to what they thought was of greater importance. Don't assume intent without evidence.
> while computers might be compromised after that date, the writer doesn't believe it's worth advising people to ASSUME they are compromised.
Which is a valid stance to have. I don't believe it's useful for the average person that has stayed patched to assume they are compromised. To assume so would mean never logging into any online account in my case. I believe it's useful to assume you are always under some level of attack, whether active or passive, and take precautions, but to assume you are compromised is quite a bit farther than that.