Twitter had issues or is it a form of user silencing?

A friend on Twitter suffered a sudden issue, he was tweeting and retweeting and messaging but nobody seemed to respond.  We tested and sure enough never received a response even though he was replying to the tweets and messages.

24 hours later to the minute suddenly everything started working again.
At first I throught the issue was with me, but he used another account he had and it worked fine.  I thought there was a problem at my end so I signed out of everything signed back in and even uninstalled and reinstalled the twitter apps.  Alas, to no avail, he was silent while others appeared in the notifications.
Hmm.   I tried switching on notifications for all his activity and nothing,  not even email notifications, we even tried unfollowing and re following each other, still nothing except for a very occasional iOS notification but again nothing in the “twitter notifications”.
Then suddenly it started working again.
What do we assume from this?
Is twitter shadow censoring users that tweet something not quite correct politically.  He had tweeted some colorful statements about a politician shortly before he was silenced.
How often is this happening?
I know that when I tweeted something that didn’t make a Bernie Sanders supporter happy she had her followers carry out a concerted reporting and I was stopped from using Twitter for 12 hours.  When someone asked why I hadn’t responded to their tweets I told them about the situation, didn’t mention the person in question that I had offended and was immediately put on another 12 hour time out.
Is it not any a stretch to presume that they can do a similar thing but allow someone to use twitter but make it harder for interaction to take place, make them feel that everyone else is ignoring them?

What happened to Twitter?
Remember how many times twitter proclaimed themselves as the social network see to be the last bastion of “freedom of speech” across the world, remember how twitter was used for many civil uprisings. Yet now they seem to be last bastion of censorship and suppression of speech.
They have been seen regularly to silence those that don’t fit the views of members of the Twitter Executive by banning them permanently.  Muting others and suspending many others.

It feels like Twitter is now circling the drain, I am sure that I am not alone in this opinion.  I am also sure that I am not alone in nurturing an account on where freedom of speech comes before political or commercial pressures.
There are others, the failure of Ello for example, adopted by the likes of Mike Elgan and other tech journalism luvvies, which promptly made it a toxic social media and it quickly became marginalized.  Google Plus, again, made toxic simply by its association with Google and quickly rotting from within, cannibalized by Google as they see fit because it is not social, it’s really a ‘look at me’ for a select few but otherwise it’s not social unless you are willing to brown nose that select few.
I think I’ll stick with,  they also have an app for smartphones.