EDIT: Though now I think of it, even with this analogy, blocking phone numbers when directed to by the government wouldn't normally threaten a phone company's status...
In Cubby, Inc. v. CompuServe Inc. they didn't moderate and were not liable as a publisher because they did not have any direct knowledge of the defamatory content as they just transmitted it.
In Stratton Oakmont, Inc. v. Prodigy Services Co. they did moderate some things and were liable due to the editorial control they had over it.
Section 230 fixed that by letting services filter offensive content without incurring liability for everything else. Without it you'd have to either do no moderation at all or perfect moderation, letting nothing offensive/defamatory/etc through.
Edit: clarity
Here's Colorado's:
> Any person licensed as a physician and surgeon under the laws of the state of Colorado, or any other person, who in good faith renders emergency care or emergency assistance to a person not presently his patient without compensation at the place of an emergency or accident, including a health care institution as defined in section 13-64-202 (3), shall not be liable for any civil damages for acts or omissions made in good faith as a result of the rendering of such emergency care or emergency assistance during the emergency, unless the acts or omissions were grossly negligent or willful and wanton. This section shall not apply to any person who renders such emergency care or emergency assistance to a patient he is otherwise obligated to cover.