how does OFAC censorship in ETH network work

I am trying to understand the whole Tornado Cash debacle.
on this website: (https://censorship.pics/) it says that 72% of the builders in the ETH network are censoring transactions according to OFAC list.

a) Can someone explain me how that really works? My thinking goes like this: "Builders" is the new name for miners. If 72% of the builders reject to take a tx into the next block and only 28% will do. It means that the chain is splitted, but that would mean that with only 28% of miners behind it, this variant of the chain will lose out quickly. And censorship will have been successfull.

b) Are there any plans to soon make this type of blocking impossible? Why are the builders even cooperating? Wasn't this the whole point of Crypto vs. paypal to be censorship resistant?

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Scratching my head looking for answers.....