That's a faulty assumption. That would be like stating that speed limit signs would not be valid if they didn't list a penal code on the sign. That's not how it works.
The second post in this thread has a link to a document that states that...
While the drone may not be able to write to an SD card at the card's fastest speed, having a faster card will benefit you when you read the data from the card. Here's a good write-up from Matt Cole of card reading and writing speeds On the...
As a friendly reminder: Although DJI no longer "forces" you to get an unlock code to fly in restricted areas, it is STILL the responsibility of the pilot to use proper FAA rules/waivers to do so.
Fly safe - Fly legal.