Omicron already in the Netherlands a week before South Africa alerted the WHO
npr.org
npr.org
In Ireland, the Health Service are reviewing select positive cases from as far back as 1 November. https://www.rte.ie/news/coronavirus/2021/1130/1263940-time-n...
This is similar to the situation we had back in March 2020. The virus was already present at least a month before, we just hadn't started testing yet...
Even as an 8yo, I understood that if I wasn't allowed to go to a friends birthday party because I had the flu, it wasn't because anyone was being mean to me!
If it was a blanket ban like Israel, I would understand. But governments placing restrictions on just Southern African countries is just performative and intended to show their populations that they are doing something.
What you describe happens so often, it has a name dedicated to it: https://en.wikipedia.org/wiki/Politician%27s_syllogism
Another example of the same... silliness was the NYC's "If you see something, say something" campaign.
This has been the same practice used all along. The action is always commensurate with the number of cases. Countries don't red list other countries based on speculation while awaiting further information (if the Netherlands has 5 cases maybe it has a million?). In my humble opinion I personally feel it would be a good idea if they did, the information isn't always fast enough - however, that would no doubt create more cries of prejudice.
The fact is, in terms of the action taken, nothing novel really happened here. Therefore, I don't see how it can be deemed punitive or prejudiced.