I’m of the opinion that having a lot of money shouldn’t, in fact, allow you to do what you want. No person should have this power to do mass censorship, not in the last place because manipulating online discourse means manipulating a fundamental aspect of democracy.
Musk specifically is meddling in elections, both in the EU and the US by e.g. bribing voters. Turning the dials of the algorithm lets him do this even more effectively.

The Google Play Store has long been the bastion for safe and worry-free app downloads
It’s nice that the article starts with this blatent lie, so that you know everything that follows is just regurgitating Google’s marketing.
Even ignoring that most of the apps in the play store are unreviewed proprietary spyware sending all their data back to Google, there have been many instances of obvious malware being distributed through the play store. It seems like they are trying to sweep that under the rug.
Sure. For the fact that many jurisdictions outside of the US also consider freedom of speech and other human rights to apply between private parties: this is called “horizontal effect” and covered extensively in case law by e.g. the European Court of Human Rights. See also this chapter for an international comparison and this paper for a European perspective.
As for the specific rules in the EU for platforms: Article 17 of the Digital Services Act requires that users who are banned or shadowbanned from any platform are provided with specific information of what rule they broke, which they can then appeal internally or in court. Article 34 and 35 requires very large platforms (such as X) to take broad measures to protect i.a. the users’ freedom of speech.
More to the point, one person who was shadowbanned by X in a similar way used the DSA and won in court
(Edited to add the last paragraph)