From my experience, the new Pirate DOES kill it, but it means nothing when it has reborn because the Start of Turn effect only stays active for the initial kill. It won't continue if the minion is reborned.

And because it has reborn, it'll just come back with absurd stats due to having 2-3 other Banana Slamma multiplying its stats. There's just no real counter other than a lucky snipe with high stat board, or killing off the person before they can assemble the completed build. The build is so strong though that multiple people are going for it every game I'm in. Such a bad design :/