no, it's not even remotely close to regulatory capture[0]. it's closer to cornering a (labor) market, which has nothing to do with the complicity of regulators here. california labor laws aren't being explicitly and specifically written to favor the longshoremen's union--that would be regulatory capture.
the main reason labor unions came into being is because companies, as they grew beyond human scale, began exerting highly coercive leverage on labor markets, sometimes via regulatory capture. some unions can sometimes exert political power, but that's not a regulatory capture mechanism, that's just regular politics.