Probably, yes. Which is why I mentioned the first part of the issue. Otoh, when the government does a takedown with court orders, there's always people yelling about it, but it's not as loud as when the government does a takedown without at least the appearance of due process or when a business does it without any due process.
> content on there is already probably illegal.
If the issue is illegal content, there should be indictments and court orders. Or at least, search warrants and seized equipment.
> If I run a business, and I know a customer is doing something like that, I have an ethical obligation to not facilitate it.
Depends on the circumstances of the business. IMHO, common carriers and businesses that are an awful lot like common carriers have an ethical standard to deliver all messages and parcels that are not unduly burdensome to the delivery of other messages and parcels.
This standard allows for blocking network abuse, probably spam, ddos, explosive packages, packages that emit noxious fumes or odors, etc. But not delivering letters because of their content isn't ethical for a letter delivery service, in my mind.