(2) that the actual thing is obviously more dissimilar to all the cited previous elements of the so-called reference class than all those elements are similar to each other (if they even form a natural category at all rather than having being picked out retrospectively based on similarity of outcome to the preferred conclusion);

Ok, it seems like under this definition of "reference class tennis" (particularly parts (2) and (3)) the participants must be wrong and behaving irrationality about it in order to be playing reference class tennis. So when they are either right or at least applying "outside view" considerations correctly, given all the information available to them they aren't actually playing "reference class tennis" but instead doing whatever it is that reasoning (boundedly) correctly using reference to actual relevant evidence about related occurrences is called when it isn't packaged with irrational wrongness.

With this definition in mind it is necessary to translate replies such as those here by Holden:

We seem to have differing views of how to best do what you call "reference class tennis" and how useful it can be. I'll probably be writing about my views more in the future.

Holden's meaning is, of course, not that that he argues <reference class tennis: (1), (2), (3)> is actually a good thing but rather declaring that the label doesn't apply to what he is doing. He is instead doing that other thing that is actually sound thinking and thinks people are correct to do so.

Come to think of it if most people in Holden's shoes heard Eliezer accuse them of "reference class tennis" and actually knew that he intended it with the meaning he explicitly defines here rather than the one they infer from context they would probably just consider him arrogant, rude and mind killed then write him and his organisation off as not worth engaging with.

In the vast majority of cases where I have previously seen Eliezer argue against people using "outside view" I have agreed with Eliezer, and have grown rather fond of using the phrase "reference class tennis" as a reply myself where appropriate. But seeing how far Eliezer has taken the anti-outside-view position here and the extent to which "reference class tennis" is defined as purely an anti-outside-view semantic stop sign I'll be far more hesitant to make us of it myself.

It is tempting to observe "Eliezer is almost always right when he argues against 'outside view' applications, and the other people are all confused. He is currently arguing against 'outside view' applications. Therefore, the other people are probably confused." To that I reply either "Reference class tennis!" or "F*$% you, I'm right and you're wrong!" (I'm honestly not sure which is the least offensive.)