The owner is doing nothing out of the ordinary. Please read this about how "change" works:
https://en.bitcoin.it/wiki/ChangeThe first transaction sends 12.25 BTC from 13Lhu... to 14mn7... and sends the change to 1N5xz....
The second transaction sends 6.25 BTC from 1N5xz... to 1uVof... and sends the change to 146wd....
I think the OP is confused about why the entire balance is being transferred to the exchange address (it is because there in only one input into the address). I think he is likely used to seeing addresses receive multiple inputs then only spend one or two (or some amount less then the total) of the inputs and only part of the money going to the change address.