Quick update - after stopping & starting demonbuddy (latest version), it detected my full inventory and properly teleported back to town to sell. If I notice it again, will attach a full log for review.
Good question - I just ran into this issue. Short of stopping the bot and teleporting to sell items, not too sure how to account for this situation. Currently using No Trash - Keep Legendary and Yellow, Sell Blue.xml as my rule set.