Wow!

This is actually a very interesting post.  That he specifies 'no previous owners' to indicate somehow that these are more pure that others which have bounced around a bit.  On the surface, you might think that is laughable.  But it is not.  Because of the discrepancies between validation systems, those coins bounced around a lot may finally get resolved as 'invalid'.  It would be on the final holder to take that loss.  Therefore, if a person had some coins on an address which he knew to be invalid on the other system (Masterchest, Mastercoin explorer) and sold those - in the end, that would be a fraud.  So, I'd rather only take coins with 'no previous owners' - than those of uncertain nature.  It is a peculiar aspect of the state of the system today.  I think it will soon be resolved.  But it is not resolved now.  Time to take a step back from the DEx and perfect the three validation engines so there is perfect agreement between them. 

Going too fast - doesn't help anyone.