Have i missed this?

@tontybear
Well said. Couldnt agree more.

Tonty I think you're pretty much spot on.

Yes VS could have communicated this better and given decent notice. But we don't know the exact reason they've done it: for all we know there could have been an incident that forced them to take immediate action.

Or, as International Hitman suggested up thread, if +1s were being publicly offered to all and sundry on Twitter VS may have had to crack down to stop it getting out of hand. A discreet arrangement between two V-Flyers is one thing but Twitter is quite another and for all we know the CH reception could have been suddenly inundated with people trying it on because they'd seen a tweet.

So yes, in an ideal world VS would have given advance notice. But perhaps they had no choice but to act immediately. We don't know so it's unfair to judge them.

Does this affect us G-class passengers too?
Can I still guest someone in on same flight or same day?

Yes, anyone travelling in UC can invite one guest as long as they're on the same flight. Whether you paid using cash or miles is irrelevant.