The ZDP added to oil is both an anti-wear agent and an anti-oxidant. Both conventional and synthetics use ZDP in similar concentrations. IF the oil is run above 305 F the conventional oils will use of the ZDP a little quicker than the synthetics due to the need for extra oxidation protection.
...Maybe they were thinking of the anti-wear additive ZDP. More of that is what you want in any oil in a bike engine. While the K4 oil might have more ZDP you can also get more ZDP in conventional oils by using the much less expensive and very high quality Delo or Delvac or Rotella products.
