It is available both for download and in cloud. So they would have to pull the download if they dont want to release source.

Pulling the download isn't sufficient if it has already been downloaded - either they have to offer the source to everyone who downloaded, or they have infringed copyright by this distribution and can be justifiably sued for that.

However, this article implies that nobody really cares about them releasing the source, as it seems that it does not have any interesting improvements.

Yeah if they pull it they need to release current modifications, but not future ones.

And they only need to provide the modifications to people who downloaded it I think.

Yes, but they need to provide the code under the same GPL license, so in practice it would be available to everyone in the world as long as a single person who downloaded it wants to share it futher.