|Wa Alaikum Salam,
The conflicts on the ruling of sighting of the moon has been worked on for decades. No outcome till today for a unanimous procedure has been established.
The ruling on sighting of the moon is “sight.” If the moon is not seen on the 29th of Sha’baan then they must wait a day and begin the fast as Nabi (saw) has said that a month has 29 days or 30 days with indications from his fingers.
In UK where the moon is difficult to see, the ruling should be option C of your description (Closest Country). As you may be aware of the incident in the 80’s i presume where there was false news received and chaos followed. Many turned to Saudi.
We have come accross “the moon being sighted by a muslim anywhere in the whole world” but have not come accross this being the ruling of Imam Abu Hanifah. However, it can be looked into if the source of this quote is stated or asked from the person who told you this.
Until a recognized, established and reliable system is established for the sighting, we suggest that the decision of the local Ulamaa should be followed to avoid Muslims in the same community conflicting in matters such as celebrating Eid on different days. This is also the decision of many Mufti’s worldwide.
And Allah knows best