I've been reading through Signal's government requests and couldn't find a similar section on Mullvad's website. I'd be curious to read about them if there are any. It would seem unlikely to me that Mullvad has never received any kind of court order for information about a user.
Yes if you get a court order for data you don't hold, you don't have to provide data you don't have access to. I wasn't expecting that Mullvad would have any useful data to give, I just wanted to read their response/commentary is all