[christophilus]

I think the author's approach is data-centric rather than object-centric.

His methods would be easy to persist: write the longs to a file. Easy to render: based on bit positions, draw a piece. Easy to understand. I looked at it and immediately knew what was happening (which almost never happens when I have to look at a massive class hierarchy). History would be trivial with his approach: since it's space-efficient, you could literally store the bit-space for each previous board configuration or if you wanted to optimize more, you could store a simple sequence of moves.