Zeigler argues that, in spit of issues with doping agencies, there should be more independent testing. Anti-doping programs done by teams principally bring up conflicts of interest, even if they do result in doping practices being brought to light.
So while the Floyd Landis hearing brought some problems to light, the agencies are moving in the right direction. In that regard, Zeigler talks about the biopassport, which he calls "a better way to go" compared to the team programs.
The reason Zeigler gives for this is interesting, and something that will only be beneficial over a larger amount of time. With the passport, athletes can be tested from a very young age, and any anomalies can be traced over several years. Once an athlete starts a large doping program, this should be visible on the passport. What Zeigler does not mention, but I think it's implied, is that teams cannot do this: they do not, as a rule, monitor riders from the age of 16 - although it does happen. To see long-term trends in all riders, you need an organization that stands above and outside the teams.
He does state, if I understand correctly, that fighting doping requires that all parties - teams and agencies - share a common goal: a cleaner sport. That seems obvious, but it does imply that not all teams are equally concerned about doping, something I have read earlier in an interview with Patrick Lefevere.