The rules of the Russian section prohibit exactly plagiarism, and not copying news headlines.
We have notes under the list of rules and here is one of the note about plagiarism:
Пpимeчaния:
8. Плaгиaт зaпpeщён, в тoм чиcлe в видe кoпиpoвaния, либo пepeфpaзиpoвaния чyжиx cooбщeний или тeкcтoв из ceти Интepнeт. Ecли выклaдывaeтe кoпипacтy, тo oбязaтeльнo yкaзывaйтe ccылкy нa иcтoчник.
Translation:
Plagiarism is prohibited, including in the form of copying or rephrasing other people’s messages or texts from the Internet. If you are posting something which is copied, you must include a reference to the source.
However, I believe that a temporary ban would be sufficient in this case because there is just one mistake, and he did it not to earn some money from signature campaign or not to raise his activity.
I didn't pay attention to the notes. I admit my mistake. Although, copying should be written in detail in article 33 of the Russian rules, so that users clearly know what threatens even a part of the text or news headline for copying and pasting.