Earlier quoted context omitted.
The problem is that the cost of Blockchain / ICO spam does not just fall on Mailchimp as a company, it falls on MailChimp's customers, who have to suffer through reduced email deliverability (for the same cost they are already paying). Other than that, MailChimp is a private company, not the government, and can damn well serve who they want.
They could use a dedicated shard of their IP addresses for sending high risk emails.
And then they have to devote engineering / moderation resource to routing emails to the correct IP shard.