No thats wrong
I've already quit and come back in the game cause dclone surprised my lvl 60 char that i was leveling lol
I could bring my mosaic and clear it no problem
But when that happened did you actually spawn Dclone already?
I'm 100% sure that if you physically spawn him i.e. you can see him on screen, then yes you can leave and rejoin and he will be where you left him even if the game is empty for a little while.
Based on my experience yesterday, he will simply not spawn if the game is active but empty while the walk happens.
What you're saying (which seems logical but who knows) is that if you get the message that he walked, you can leave and rejoin the game BEFORE triggering his actual spawn location, and he will still spawn after you rejoin?