[akerl_]

If somebody says something rude to me, why would my reaction be to try to decide if I’m glad they were rude unintentionally?

[jtbayly]

Reread what I wrote. The point is it is more rude to assume somebody is ignorant than it is to assume they are knowledgeable.

This is telling people to assume people are ignorant or at least pretend you think they are ignorant.

[danaris]

As akerl_ says, it's not telling you to assume anything. It's talking about behavior, not thoughts.

You can be thinking they're the most ignorant fool on the planet, or you can be thinking that a minute ago you believed them to be so smart, and now that image of them is shattered and you're disappointed...but all this is asking you to do is not to perform that surprise to them, regardless of whether or how much you feel it.

[akerl_]

It's not telling people to assume anything at all.