THEY’RE IN A VIRTUAL WORLD. ONLY THEIR MINDS ARE PRESENT, NOT THEIR BODIES.
AND YOU KNOW WHO ELSE HAS A MIND BUT NOT A BODY?
If you apply the hardware-software metaphor, it’s possible for Atem to be present in Noa’s virtual world even though his soul is attached to the puzzle. And seeing how the Big 5 can still separate themselves while sharing Tristan’s form…
THEN THAT MEANS ATEM COULD’VE SEPARATED HIMSELF FROM YUGI AT ANY TIME IN THIS ARC. SERIOUSLY.