Indeed he did. However, if a user clearly provided a source he got the info from, it's a bit difficult to argue he's trying to pass the content off as his own.
If you say "I think that <copy pasta follows>" what other intent is there? I'm not arguing for a permaban here but I think (and this is indeed my own personal thought LOL) that we are getting bogged down in technicalities too much. Yes,
technically a source was provided. But someone reading text like that would reasonably assume that it's indeed the person's own thought. IMO moderators can and should issue a warning / edit the post / delete the post / tempban the user / use other non-fatal tools available to them in cases like that, depending on the severity.
Reminds me of some trolling sockpuppets that are getting a free pass because
technically we can't prove they're sockpuppets, ban evaders, etc with some bulletproof blockchain evidence... so they go on even though there is zero value in allowing them to continue.
I've expressed my own personal opinion on the matter - other moderators can (and some probably will) disagree with me and crack down on it much harder than I would. Do note that I'm not arguing for these posts being completely-100%-a-okay, more so saying that unlike regular plain plagiarism (taking content and posting it as your own without a source) such actions won't get you a permanent ban for a single post. Depending on the context (e.g. it's a single post / topic or it's a recurring pattern within a user's post history) and content, the post itself may be considered as low value but that's going to have to be decided on a case by case basis. Same with what to do with such a post / topic (delete, edit, lock, leave it be, etc.) and the one who posted it.