Disclaimer: I'm not at all against the addition of more GMs to the Zuma, as long as it's done well; I just feel that there are some counterarguments that need to be made to the specific points in question.
Having multiple GMs run the Zuma in the past hasn't (from all I've seen) "improved the flavor", all it's done is add to the confusion, as one GM says one thing and the other says or does the opposite.
Having multiple GMs run the Daimons in the Fourth Invasion caused some serious problems both from an IC and OOC standpoint.
From everything I've seen in the Zuma thread, doing this would not pacify everyone. It would pacify you, because your particular beef is that there's one person running them. However, the way I read some of the other people's arguments, they object to the very fact the Zuma exist as a GM-controlled group in western Dwilight.
In all likelihood, the actions and policies of the Zuma would not change even if there were 1-2 more GMs added, as these actions and policies flow from Tom and the established Zuma RP—that which is known to the GM him/herself, not just that which is public to everyone.