How and where does YouTube present itself as being "agnostic" to content?

And if you think it's only natural that YouTube disallows "propaganda" that "reasonable people" would object to, why are you surprised that they would remove other varieties of propaganda? Of course, different people will have different definitions of reasonableness.

You’re implying that there is a legal difference between being a publisher and a platform, which is not actually a thing under US law.

Then why was this legislation introduced ?

https://en.wikipedia.org/wiki/Section_230_of_the_Communicati...

Section 230 does not require that YT or any other service be neutral. It is extremely common for people to represent 230 as if it requires neutrality, but it absolutely does not.

Here’s the entire text of 230, it doesn’t have a “unless they’re biased” clause.

> No provider or user of an interactive computer service shall be treated as the publisher or speaker of any information provided by another information content provider.

I don't believe that was the point GP was trying to make.

You're correct that section 230 doesn't require neutrality, but that was part of the point of the legislation. The case law prior to section 230 did result in such a distinction, though not necessarily in those terms.

The cases in question are:

- Cubby, Inc. v. CompuServe Inc., in which CompuServe was held not liable for content hosted on its systems as it was merely a distributor and did not have knowledge of the content, and

- Stratton Oakmont, Inc. v. Prodigy Services Co., in which Prodigy was held liable for defamatory content posted on its systems as it performed moderation and was therefore considered to have editorial control over the content

Section 230 introduced a carve-out for internet service companies to avoid liability for user-generated content, but given the case law it does seem like this is otherwise a distinction made in US law.

It was a distinction made in US case law, until Section 230 rendered it moot. Section 230 was in fact written partially in response to Stratton Oakmont, Inc. v. Prodigy Services Co., because the ruling was considered such a threat to the growing internet.

Youtube also presents itself as an international platform, so what you say about ISIS might have very different perceptions e.g. in comparison to a US Navy ad in the US than in the Middle East. Or do only US standards of what is reasonable free speech apply? Why is porn obviously not free speech less than lizard people conspiracies (that's what Dike is propagating).

No they don't. YouTube is very clear that they will remove many types of videos, and even ban accounts.