IMHO I believe it would be helpful to augment rule 66D or create a separate rule that would allow a TD to remove an "abandoned" chipstack (due to re-entry) from play.
The last rule of the 2015 TDA rule set states
D: Chips of a disqualified player shall be removed from play.
With the increased proliferation of RE-ENTRY tournaments (many of which allow the player to abandon a chip stack), it seems appropriate to augment or add a new rule that would allow the TD to remove the abandoned chips from play.
This would allow for the abandoned seat to be occupied by a new player or alternate. It also removes the advantage that would be gained by the player to the right of the abandoned stack (if the stack remains, the player to the right would have his own button position and then button position when the abandoned stack has the button)
Such a rule would impose some logistics for the TD to be aware of the abandoned stack and remove it as soon as possible. That is, when a player is disqualified by the TD, the TD is well aware of the situation and can immediately remove the stack, but when a stack is abandoned, the TD would need to be notified and then remove the stack.
Granted, a house could impose a local rule to cover the situation, but a specific TDA rule would help create a better procedure to follow. It would also help to create a consistent rule for tournaments that span multiple casinos.
Like the case of the disqualified player, the abandoned stack should never be allowed to place in the tournament, hence, removing that stack would be consistent with Rule 66D. The TD just has to be aware of the situation and remove it.