No, you're right. The comment you're replying to is specific to Chrome. Firefox behaves as you describe, though personally I still strongly prefer TST's behavior; it's a substantial further improvement over Firefox's default setup. Especially when you add in container tabs, and the ability to prefix url bar searches with % <space> to search through your open tabs.

Some people seem to strongly prefer Chrome's behavior. The only advantage I can see is that it forcibly prevents your tab count from getting out of hand.