My mistake, you are correct.
I don't know if you've seen self-defense referred to as vigilantism in news articles, but I have. Can't provide a link, as I'm just going from memory, but I've read more than one account of a sheriff or a police spokesman referring to an event where a homeowner shot an intruder as "vigilantism". Ugh. So, I tend to get particular about the usage of the word.