> Mind you he still that the bottom spokes of a wheel are in compression

I think you might want to read pages 7–8 again: "Wires must be tensioned to prevent their buckling under load. With tension, wires can support compression loads up to the point where they become slack. The same loads that increase compression in wooden spokes, reduce tension in wires. As in algebra, where negative and positive numbers are combined to give algebraic sums, in spokes tension and compression are the negative and positive forces whose sums depends on built-in spoke tension and the carried load."

So the bottom spokes can support a compressive load because this is smaller than their unloaded tension.