Of course here you're correct again, but the point I wanted to show with the example was not a technical similarity but a similarity regarding the legal concept of intent (or dolus in Latin). Both a BTC node and an ISP helps in distributing the data, but none of both has the intent to do it; the darknet forum containing the link can have such an intent though (although not always).

Here's a Wired article of Narayanan and others which supports this opinion and compares Bitcoin node operators to Tor exit node operators, which is actually a better comparison than nodes <-> ISPs.

Of course, ill-intentioned lawmakers could model the law (e.g. in the case of a moral panic) in a way open and immutable blockchains become impossible, but that's why I wrote that Bitcoin users should fight for that not to happen. Freedom of information movements have scored some victories in the recent past against over-restrictive regulators. And according to some studies, there's hundreds of millions of bitcoin users in the world which may be an attractive group of voters for politicians.

It's funny that the Wired article also mentions a possible solution that I've thought about a bit in the last days. One could make OP_RETURN data completely deletable, for example if their hash is recorded separately. In this case, even a "notify and take down" system could be implemented. The problem would perhaps be that the set of nodes offering the "full" blockchain with the data would decrease, in an extreme (but in the case of BTC, unlikely) case even to zero.

I would be more comfortable with such a system than to restrict scripting. You may not agree but I believe that "unapproved" innovation with scripts must be possible as a manual "whitelisting" very likely will be extremely slow.