'Arbitrary' was the wrong word, projections encode information.
The more charitable 'random' is a null hypothesis. It is formally impossible to prove. It is uncomputable.
So it is not surprising to see someone reject the null.
The fact that it was given any credence suggests to me deep problems with interpretability or ai safety in general.
Take the headline here: "interpretability might be the most important scientific problem in the world right now, as I don't think we can solve alignment if we don't know what we're building."
I deny even the existence of alignment. In my view, the field of 'alignment' works on a problem that does not exist.
Alignment is a reference to something that does not exist in the model: social norms. It will never be intrinsic to the model. You will not find it there.
'Neurons' are not primitives either, they are not intrinsic to the model. 'Neuron' is a human-constructed category. It is easy to just make up intrinsic properties of neurons and get away with it.