With a source, OP is fine from plagiarism. I don't think the forum is too strict and requires people have to leave initial sources to not be considered as plagiarism and get account restrictions (perma bans for this rule break).
It's not about plagiarism, really. It's about the post
quality. If you just republish an article on the forum, not really adding that much to it (usually, users post one/two sentences if that), then should we not consider the value that the thread gives exclusive of the article contents? If you look at the post at what the
user brought, then you have their couple words and the fact that they found an article to share.
That's what I want to concentrate on stopping.