The bar is pretty high for a complaint. You have to go pretty far out of your way to do it. Two people complaining about the same license plate seems like a lot....especially in Manitoba, which is not a terribly densely populated province.
First, to the question of offense. It certainly seems to be the case that no offense was intended. As a reference to the Borg, I get that it's not actually aimed at indigenous people. That said, a license plate doesn't offer a lot of context. If you drive a car with such a message on it to a Star Trek convention, people would probably understand the context properly and interpret it as intended. However, drive the same car around an indigenous reserve in Canada, and you might reasonably reach a very different conclusion, because the context suggests a very different intention. Perhaps the license plate holder could add the needed context, but it's far less prominent than the license plate, and some people may miss the significance or the reference. I do not think it requires exceptional sensitivity to have an issue with this, especially as the placement on an official license plate seems to lend the voice of the province to the message.
To the question of whether the loss of the license plate is a reasonable remedy, I would say that it is. I don't know how Canadian law treats them, but in the US, license plates are seen largely as an act of state speech, not personal expression. That distinction has allowed states to set limits on the contents of license plates. And it's important to note that no restriction has been placed on the message, were it displayed on any other part of the car that doesn't appear to issue from the province of Manitoba.
In the last 24 hours, the President of the United States's chief of staff has discussed changing the libel laws to make it easier for him to sue reporters for reports that he does not approve of. And this is what you're worried about??? Are you capable of worrying about free speech in any context that doesn't involve attacking "leftists"?
