It's an anti commercial license. The thought is that, they don't mind if people copy their comments, save them, re use them, etcetera, they just don't want people to make money off of them, likely this is a response to AI companies profiting off of user comments

However I'm not sure if just linking the license without context that the comment itself is meant to be licensed as such would be effective. If it came down to brass tacks I don't know if it would hold up.

Instead they should say something like

'this work is licensed under the CC BY-NC-SA 4.0 license'

I'm also not sure how it works with the licenses of the instance it's posted on, and the instances that federate with, store and reproduce the content.