Because supporting that censorship is good with the excuse that criminals need to get punished is suspicious. Censorship is not justified when it goes beyond the bounds of justice, and zkSNACKs was beyond the bounds of justice.
How is saying "I'm not going to do business with you" beyond the bounds of justice? Libertarians believe that entrepreneurs have the right to decline a business deal, why do you believe that people should be forced to trade with people they don't like?