Why is it every instance admin's responsibility to fix bigots? What is it about running a Lemmy instance that obligates people to actively work to find the one glimmer of redeeming quality in these human septic tanks? Why should the targets of their hatred have to do all the work to avoid being victimized?

Well it isn't, nothing does, and they shouldn't. Bigots are the ones in the wrong here, and kicking them out works plenty well. Bigots spread by being given platforms. Take away even one of those and it lessens the spread.

"We shouldn't have echo chambers" is just propaganda from bigots who were upset that their soapboxes got taken away. Stop falling for it.