On the one side, they have been asked for information about two very specific instances, and the court should be able to judge whether the particular comments matter.
But what does the newspaper know? They maybe have an IP address logged, and they also are likely to have an email address. Connect from a wifi hotspot, and have a few email addresses trawled, spammer-like, from the net, and you can make that useless.
The trouble is that the old-style anonymous informant is filtered by a reporter. There's a choice made, and often the reporter ends up knowing who the informant is. That relationship, and that knowledge, deserves protection.
If I choose to "post anonymously" here, I don't feel I should expect the same protection. This is still me in a public place. If I want that protection, I think I should be sending a personal email to a reporter.