I don't think it would be necessary to screen these comments by default, since they're essentially anonymous comments, yeah. That said, there should be support for letting the journal owner choose to screen them by default if they want.

if you check out the Privacy tab of the account settings page, there are three options there that are relevant in this situation, I think: "Enable Comments: Allow comments from [everybody/registered accounts/access list/nobody]", "Comment Screening: Screen [no comments (don't screen)/anonymous comments/comments from people not on my access list/all comments] before displaying them to others", and "Anti-Spam: Show CAPTCHA to [nobody/anonymous commenters/people not on your Access List/all commenters] ". With adding this level, I think it makes sense to include the additional option there.

(Our general anti-spam setup is to let users manage it themselves, and when they get a spam comment let them delete it and put it into our site-wide antispam system for us to block the spammer. I would not be opposed to adding a moderation-queue type deal, but I think it is way outside the scope of this project.)