The linked article states "certain invited speakers and participants remain subject to pending administrative and security clearances, which have not yet been concluded".
I have friends who organise conferences as a $dayjob, including in countries where political and government clearances are required for conferences attended by speakers and participants from external countries.
These clearances are typically required for BOTH the event AND each foreigner individually (and the foreigner will often be unable to even apply for, let alone obtain their visa until they have the clearance).
Lets just say that organising a Human Rights Conference in such a country would probably not be the smartest idea in the world.
Even for an uncontroversial conference, the clearance process is excruciatingly painful. I dread to think what it would entail for a Human Rights conference !
They took the risk. It didn't pay off.
Hope they had solid events insurance to cover all the costs.
'Oh its canceled, well shit.. guess we can't do ANYTHING now.'
What?
The government of the host country said some of the themes were potentially at odds with their national policy, and they weren't sure they liked some of the people involved.
That doesn't sound like anyone was threatened, it sounds like they should have picked somewhere with a stronger tradition of free dialogue.
I could be wrong, but I suspect visas may be affected as well.
The organizers and attendees will try and coordinate something else. However, throwing something together on zoom, at such short notice is going to be a crap show.
The schedules wouldn’t survive unscathed, since speakers will start dropping out at this point.
If they do manage to get something together, they run the real risk of it being a rickety and frustrating event.
The fact that both are equally likely tells you all you need to know about the current state of the USA.