The quadrupole moment of Venus is much, much less than that of the Earth. For comparison, the relative difference between the radius at the equator and the radius at the pole of Earth is about 0.3%. For Venus it's less than one part in 100,000. However, Venus doesn't have a moon, so there's no third body to cause Kozai-Lidov oscillations [1].

[1]: Actually, this is not strictly true, since the Sun acts as a third body. However, it's so much further away that the Kozai-Lidov effect from the Sun is weak. That's why the Venus Express was able to maintain a polar orbit around Venus.