Agreed about the 0.5nm apart if you ignore the fact that the intersection is approximately 1.4nm from the threshold of 34 and 0.6nm from threshold of 27. So you gain about another 0.8nm.
The aircraft on 34 was 0.5 miles closer, so you need to subtract 0.5 miles from 0.8 miles, not add. It puts the aircraft on 34 0.3 miles behind the aircraft on 27 (without allowing for rounding or wind).
But the important question is not so much exactly what happened in this incident.The important questions are:
Is LAHSO conducted in a way that always allows simultaneous go arounds from both runways at any point in the approach without compromising separation,
and
If not, should it be?