I spent a lot of time dealing with phishing and fraud prevention. By far the biggest source that I had to deal with was free service abuse and near non-response from those service providers abuse teams.
Let us not forget that these emails aren't even being sent by or through Cloudflare: Cloudflare is not an email provider. Their interest in this is simply that they provide DNS. I find the ways that cloudflare thinks about how we should stop Internet abuse--such as their plea that all ISPs turn on packet logging to help find the sources of denial of service attacks--extremely concerning from a surveillance perspective :/.
You abuse a service, the service is terminated, you got to utilize it for a while and suffered no penalty aside from having to sign up for a new account.
You use a stolen credit card, the service will be terminated and now that stolen credit card can be reported for abuse as well.
A legitimate account that is paying for service and has legitimate contact information can actually make contact and rectify the issue, clear up a misunderstanding or be made aware that their domain is being abused in some way.
I signed up for Sendgrid a few years ago for a company that I worked for and we used it to send the company's first newsletter to 300,000 users in about 14 years. About 70,000 of those bounced and somewhere shortly into delivery process, Sendgrid halted it and called us demanding to know where we got our email list and insisting that we verify user information for multiple addresses that had bounced.
Once we explained the situation and verified everything, they released the halt and that first volley continued creating records for which email addresses we shouldn't be sending to again. Everything was fine from that point forward...but even with a paid account they were actively working at fraud prevention...and as long as there was a legitimate contact on the account it was perfectly reasonable to get resolved.
I have little confidence in this working in the defense of an ideology that gives the host bad PR or the deplatforming of which would give it good PR, like in the case of The Daily Stormer.
Recent history should make it abundantly clear that private entities feel no obligation to defend noble ideals like freedom of speech, nor should they, being private entities. Paying for their services shouldn't change this meaningfully, especially where even Western governments like Germany's and the UK's are similarly illiberal (in the traditional sense of the word) and pressure those companies to remove "hate speech".
It was a very unique situation, in all honesty.