There is actually lots of contradictory evidence that Queen and King were restrained and imprisoned. Here this is one of them I found on WG forums that actually made lots of sense.
-Both being
Ancient Zoans boasting high durability and recovery. On top of that, Queen has metallic cyborg parts that make his body sturdier, and King has his Lunarian genes that make him more durable. If
Jack (who's weaker) can get up within minutes after getting downed in Onigashima, then so can they.
-Following the previous point, 7 days have already passed, making it even more likely they would get up. I'd argue Zoro received more damage from the Hakai in the roof top than whatever damage King and Queen received, and yet, here he is after a week, awake and energetic.
This is a man without a Zoan's durability and recovery speeds:
-There's beer on the outside, implying they were drinking. Also, it doesn't make sense for Green Bull to throw that remark at them to age the booze if they weren't drinking it themselves...
-King and Queen were the
ONLY Beast Pirates members to be thrown
OUT of Onigashima. With
Queen being the
ruler of Udon prison, who has been numerously wondering what happened to his turf with Babanuki acting suspicious, it can be easily assumed that they went back there to check up on him AND recover while at it.
-They are
NOT inside prison cells. Oda made it clear with the background drawing of the recent chapter that they're inside Udon BUT outside the cells itself.
You can clearly see the sky above:
THIS is what
INSIDE of a cell looks like:
THIS is what
OUTSIDE of a cell looks like:
-You can see one of the watch towers in the area that were destroyed by Big Mom's O-Lin rampage long ago, further emphasizing this is happening outside cells.
And while we're still looking at this same panel, notice how the cuffs on Luffy's hands are positioned? they're restraining his arm movements by keeping both hands close to each other.
But with King and Queen, their arm positions imply their hands are free and without cuffs...
-Therefore, as everyone else already mentioned, there are
NO Seastone cuffs or any sort shackles shown in the scene.
Final Point (nail in the coffin, if you will):
-In every single introduction of Admirals we got, Oda always made sure to showcase their powers and establish them as threats. Whether it's Aokiji dispatching the Monster Trio without sweat, or Kizaru whooping the floor with half the Supernovas in Sabaody, they're always portrayed as intimidating opponents that make quick work of anyone they encounter. It's a no-brainer he would do the same with Ryokugyu too.
So why would he have the victims in this case be weakened? that defeats the whole point of the introduction:
to generate hype.
If they were really nerfed, the average reader would say "meh he just finished them off cuz they were weaker anyway".
That's not what Oda wants his readers to think. In fact, Green Bull coming to Wano in the first place wouldn't have been a
big deal if he's just picking on weak people like this.
Just look at this dialogue speech bubble and tell me honestly what its saying:
"give it a rest"
give what a rest?
"at my rank, I'd lose face if I let a few commanders like you get the best of me"
get the best of you? so they were TRYING to BEST YOU...?
Tl;dr: Oda wouldn't introduce a new Admiral just to have him shamelessly take out weak opponents. This won't establish his threat and power.