There has been some discussion around this lately. The wording on the website was recently changed to make it seem like this is only the case if the Gold member is traveling on the same booking (“your fellow passengers”) as the non-status or MVP pax. While the discussion was around change fees, I suspect if true, it would apply to the SDC fee as well.
The wording now says:
As an MVP™ Gold, my change fees are waived. What about for my family?
While anyone traveling with you in the same reservation will have their luggage fees waived, the change fee will apply to all passengers other than the MVP Gold. The exception is if your fellow passengers are booked on an award ticket using your miles; in that case, change fees are waived.”
See the discussion here
Policy Question - Change Fee
And in particular,
https://www.flyertalk.com/forum/30270476-post3.html and
https://www.flyertalk.com/forum/30271252-post4.html
It is a little vague and I’m not sure we have any data points to confirm or deny this change out in the wild yet but it does not seem like it (a change fee waiver on tickets booked with Gold miles) is a sure thing anymore.