That's because there are no facts. We don't even know if the internet was cut in the first place. (One wonders how they managed to post to Twitter without internet access.) The "state actor" part is completely unsubstantiated.
The third option you've missed is "this is all bullshit." Either because it's not happening at all, or because the embassy's internet is down due to some routine outage.
I meant in this particular case it would be weird, because it would mean that the perpetrators are somehow blocking mobile data but neglected to block SMS.
I think a state actor could filter at will, since they could MITM the connection and pass stuff through selectively. Not that I can see why they would bother. Although I can't see why they would take this action at all, which is why I don't believe the story in the first place.
"(One wonders how they managed to post to Twitter without internet access.)"
I don't think Assange runs the wikileaks twitter account. So probably he messages them every day and when they don't get a message they know something is wrong.
The third option you've missed is "this is all bullshit." Either because it's not happening at all, or because the embassy's internet is down due to some routine outage.