But how hard would it be to make a decision? Unless it's actually costing MNHQ to set up a different board?!
Its presumably a cost benefit analysis as it would be for any other site.
And yes, of course it has costs associated with it - why on earth wouldn't it? There is both the cost of managing/maintaining a separate topic (especialy one made mandatory for that subject) and the cost of fragmenting traffic which is often less obvious.
The asks on here keep growing so that its not just a separate topic but also for the threads on the subject to be hidden from active and trending and actively moved into the "quarantine" space so that the whole subject is rendered invisible unless you happen to know its there and go looking - OTBT for Ukraine. Because gods forbid adults should be expected to manage what they read in any way at all.
I wouldn't mind betting the cost of managing the covid topic has been pretty significant in terms of mod time alone and that is one factor going into the decision making.
They also have the benefit of actual numbers of Ukraine related threads every day rather than the perceptions of individual posters.
For me new topic/no new topic is simply a matter of numbers and traffic on the subject. Its the wider policing of the subject which is being demanded that I have issues with. I'm an adult, its my responsibility to hide AIBU/chat at times when I just don't want to risk seeing subjects to which I'm sensitive at the time.