Honestly, I think the quantum sequence demonstrates that knowing about mental biases isn't enough to avoid falling to them.

I would argue this whole series presents a false dichotomy (many worlds vs. copenhagen). There are many more potential interpretations- there are even no collapse interpretations that rely on a single world. Ensemble/transactional/objective collapse,etc. None are discussed, but all are dismissed.

Further, Yudkowsky confuses the map with the territory in a spectacular fashion. The territory is a series of experiments where scientists can't make specific predictions (and instead can make predictions about classes of experiments). The map is quantum mechanics. Yudkowsky suggests we should believe many worlds, in part, because to do otherwise would require the only non-deterministic rule in physics. Well of course it is- this is the first (seemingly) non-deterministic/probabilistic territory physics has tried to map! Should our instinct, when we find an area where the old map doesn't work, be to assert that territory itself is wrong? Experiments only APPEAR non-deterministic, but really....

Its no surprise that physicists attempting to extend their map would create a deterministic model and graft a non-deterministic component on top- deterministic systems are where they learned cartography (to extend a metaphor). There are active efforts to describe collapse by adding a stochastic term to schroedinger dynamics- why should we take these less seriously than many worlds?