If you try to pick up the chain after you freed Byron the game acts as if he's still there, the dialog plays. Greyed out, though.
And the game crashed. Some time later, that is. When talking to Hoxton.
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in "GlobalScript.asc", line 1653
from "__DialogScripts.asc", line 12
from "Dialog 4", line 78
Error: FaceCharacter: characters are in different rooms