i am not quite sure what spin this post is taking..
yes, it is true there are players that make their way back under new or even old id's... often times the thought process is that players change, get older, get wiser, mature, repent, etc. etc. etc. and a second chance to be part of the group is extended... some make it... some revert to old ways and disappear again..
As for TD's turning their backs, i am not sure what you would propose they do? First, TD's haveno way to know who has been removed from the system or for what reason, or if they have just changed to another ID.. so there is really no recourse for them... if the system allows an id to join, play, etc. then as far as the TD is concerned, that is acceptable...
I am not sure where any of this is counter to a fair league, and even in many of the highest regarded famiy oriented families there appears a black sheep once in awhile...