No, it was a legit question. It depends on the payload though right? For StarLink deployments at LEO, I'm sure it re-enters soon-ish. But what about for higher altitude launches of other types of satellites? How long does the second stage float around?

If you have questions I'd suggest asking them as a question. Your post read as a statement of fact with a rhetorical question attached.

"How long is the second stage just floating around after delivering payloads?"

How much more of a interrogative statement does it need to be made to be considered asking a non-rhetorical question?

If you take it out of context of your post, yes, it looks like a well posed question. When read in context it looks rhetorical and that's how I took it, too. Perhaps you didn't intend that. But that is how it came out.

As a standalone question that's fine, but in context it's a rhetorical question as you already state your assumed answer.