If they in fact can't transmit, then this is OK. If they can or, even worse, have a long latency period and will show symptoms in 2 weeks, that is very, very scary.
Our best tool for diseases like this is contact tracing. And asymptomatic carriers make that very hard.
(Useless trivia, the first documented asymptomatic carrier who was infectious was a short order cook named Mary Mallon. She is better known as Typhoid Mary.)
When she was first identified, she cooked for a number of families. The outbreak that got her put away for life was due to working as a cook at Sloane Hospital for Women.
I cannot immediately find record of her being a short order cook specifically. However that is my recollection from https://www.amazon.com/Betrayal-Trust-Collapse-Global-Public...
Do you have evidence of that in this case?
Viruses vary widely on how many are asymptomatic. My understanding is that having people be infectious and asymptomatic only happens with diseases that are well-adapted to their hosts. Which this one, having recently crossed a species barrier, isn't. (Its fatality rate is also high for the same reason.)
However that is a general understanding and I don't have data to base it on on this case. Do you?