Your numbers say that 92% of the time a honest contributor would not have performed so poorly. That's is enough reason to freeze payments until more information is available.
If DrH was to freeze funds for every miner that ever had reached the point where they had submitted 2.5*D shares and only solved one block, nearly everyone who has solved more than one block would be very pissed off.
I can almost guarantee you that at some point
you will have submitted 2.5D shares for one block.
I can guarantee you we have solved blocks worth substantially more than we have been paid.
Multipool has been paid 4x what they have contributed to the pool. Maybe you think a $50k donation from all the other users of this pool is trivial. I do not.