They can only offer Internet in Iran with the (implicit) blessing of large nations.
The specific act of offering Iran may or may not help China, but it clearly undermines Russia and helps the US.
Regardless of that, unauthorized deployment of uncensored Internet is a strong political weapon that is only available to large / wealthy nations.
(Contrast this to some sort of hypothetical censor-resistent NNTP style news source, where cheap devices sync the news with each other via local wireless connections.)