It depends so much on the exact scenario. I believe we’re imagining radically different QC development scenarios rather than disagreeing on specifics. Eg see below.

Bitcoin has maintained its neutrality precisely because it only has value if it maintains its neutrality - the market in general will sell any fork that isn’t clearly in line with the properties of Bitcoin that matter.

But there are other market dynamics like supply that matter too. As Pieter puts it, Bitcoin only works if everyone in Bitcoin can agree to the secure set of cryptographic primitives in the system - for those not okay with pre-QC crypto and okay with “you had ten years to move your coins, and even if you forgot we’ll make sure you can still get them in every case we can”, they’ll strongly prefer the fork with fewer coins being sold (not just total supply, coins on the market!). IMO that’s a *very* reasonable position (again, as always, depending on exactly when/how/etc a CRQC is discovered/built), especially because that position *allows more bitcoiners to retain access to their bitcoin*.