> What they meant when they said "planets"

Who is "they", and how do you know what they meant?

The relevant fact is that the claim "Exoplanets also aren't planets" is simply wrong -- exoplanets are by definition planets outside the solar system. It's like claiming that a brown furple isn't a furple -- the claim is wrong, regardless of what one thinks a furple is.

> The reviewer of this paper is saying that by biology they always meant naturally evolved cellular biology, not synthetic biology - there's just never been an example of the latter before.

They aren't saying that, and that isn't true.