> personally attacking your audience is not an effective writing technique
Absolutely true. So whenever a writer appears to be attacking their audience, you may have misidentified the audience.
Assuming these guys have been fighting the good fight the whole time, I can see why a hail mary switch in tone could be warranted. They're losing. Just staying the path and being agreeable and conciliatory would be what is pointless.
In general, encrypting email is a good thing in the same way enabling TLS is a good thing. One can quibble about the details, but it is absurd and harmful to suggest it should not be done at all. So the snark seemed fairly unreasonable in this article as it doesn't addressing the root issue.
To me, the condescending tone of the writing is masking inherent flaws in the argument being made. It's hard for anyone to challenge someone who obviously knows more than them when they appear to be obviously wrong, the condescending tone discourages discourse that would otherwise have lead all involves parties to a better understanding of the technical subject.
In general, personally attacking your audience is not an effective writing technique.