No, it’s completely right. At the time of writing, it did literally mean all able men of fighting age. This was determined by the supreme court in 2008. That’s not to say there weren’t specific militia organizations, but it’s not what the amendment is specifically referring to.

It’s worth noting that at the time of writing, the words “well-regulated militia” referred to all fighting age men of sound mind. It wasn’t a thing to join or train for.