This is ActivityPub, not Reddit. It is optional, democratic and auditable.
People are not sending posts/comment to be approved first, you can post whatever you want. It is a plus if the community found a bad faith actor and tagged them. So I am not forced to see their disinformation campaign.
I don't think it would be taboo to save something that is public available, as you can just as simple visit those pages and print them to pdf for example.
The same goes to things you have access with your account, and it is not bound by a non-disclose agreement (you can still save, but not broadcast it - depending on the laws of your jurisdiction).
I looked into the lemm.ee default profile page, and you might have success with the tools I mentioned.
You just need to navigate these links, and make the tool open the post names.
https://lemmy.ca/u/megane_kun@lemm.ee?page=1&sort=New&view=Posts https://lemmy.ca/u/megane_kun@lemm.ee?page=1&sort=New&view=Comments
You will need to take in account navigation with "next" buttons, and some pages need to be scrolled down to load all the comments.
If you don't want to contact the Admins, and you are not pressed for time, put a delay on the tool's web requests to not overload the servers. The browser add-on might avoid that because it mimics a more natural way of navigating a website.