As written, the provider protection would only disappear if they are the creator of the content they make available, or if they altered that content, in which case they would be subject to the publisher rules.
The publisher rules would likely protect them as well and may even require them not to publish that content, since there's strong evidence that the content is defamatory: (1) a random computer service tech apparently received a computer from a guy he claims to be Hunter Biden (2) but he can't actually say the person was Hunter Biden, (3) the customer never came back for the computer, (4) the computer service guy was able to get into the computer and look at the email but the only evidence is a blurry screenshot,(5) the current possessor of the computer is unwilling to turn it over to any third party for forensic analysis showing that the email actually exists, and (6) the timelines in the purported email don't match reality based on confirmed travel by Hunter Biden or the person he supposedly met with.
Regarding point 6: The defense used by the Biden campaign was very specific, to wit: we have reviewed Joe Biden's official schedules from the time and no meeting, as alleged by the New York Post, ever took place.*
If I were going to hold a covert meeting with foreign nationals that falls afoul of anti-corruption laws, I wouldn't be putting it on my official schedule either. This is not a defense to the accusation made.
I still want to see the raw emails. PDF screenshots aren't trustworthy, but the DKIM-signed messages with headers would confirm authenticity. Another thing that lends credence to the legitimacy of the hard drive are the photos taken from it - these too are in the NYPO article.
Also, there's a lot of stuff about the hard drive that doesn't add up. Hunter Biden lives in California but supposedly dropped off the laptop in Wilmington...on a weekend while he was seen attending parties in Los Angeles...with his (then) fiance. And the laptop was given to a legally blind tech shop owner who can't actually say who it was that dropped off the laptop. The tech shop owner then made a copy of the hard drive, and then gave it (the copy) to Guiliani rather than the FBI, and Guiliani kept it...rather than giving it to the Senate committee investigating the matter at the time. The FBI didn't purportedly get the hard drive until sometime earlier this year...after the Senate investigation had concluded without finding anything. If there actually had been something on the hard drive earlier this year, why didn't either of them turn it over to the FBI or the Senate committee earlier? None of this makes any sense, and a lot of it sounds made up.
If I were going to hold a covert meeting with foreign nationals that falls afoul of anti-corruption laws, I wouldn't be putting it on my official schedule either. This is not a defense to the accusation made.
And yet, that is precisely what two of the sitting President's children have actually done, as well as at least two of their spouses...
But on that note, at the time of the purported meetings (2014 and 2015), Hunter Biden was the son of the sitting vice president and would have been under Secret Service observation. And yet, the Secret Service doesn't have any records of such meetings, or even of Hunter Biden traveling to the cities where they meetings would have taken place.
I want evidence that any of the purported evidence is authentic. If this were any other administration, that wouldn't be an issue. But the Trump administration, and Giuliani especially, have such a long history of fraud that you simply can't trust anything they provide.
The more pertinent question is, as you said, whether the info is authentic. The origin story, ultimately, isn't important assuming the information is confirmed.
Guiliani has played a role as a conduit for multiple prior Russian disinformation campaigns. Guiliani also confirmed after our original discussion that he provided the purported emails to the NYPost because he knew they wouldn't verify their authenticity, and has since refused to provide the emails or the laptop to any other news agencies for forensic analysis.
The leading theory is now that Russian intelligence hacked Hunter Biden's social media accounts, stole a few pictures to plant on a laptop with the fake emails (to make the emails seem authentic) and they then provided the laptop to the tech shop owner. Their primary mistake, as previously noted: on the day that Hunter Biden supposedly dropped off the laptop, and the day before, he was seen partying in LA with his fiance, and could not physically have made it to Delaware in time to visit the tech shop that day.