I guess a lot depends upon how you define a 'liberal'. In the proper English sense of the word, it means someone who is willing to respect or accept behaviour or opinions different from his/her own, and is open to new ideas.
That seems like a good thing to me, and I certainly hope the mods are chosen from people who are liberal in that sense (VIPs have only an advisory role, so it doesn't matter as much).
If you use 'liberal' in the American political sense, it may mean someone who is not a conservative, and interested in stuff like social welfare, and generally socialist things. I don't know all the mods and VIPs well enough, but I don't see many socialist points of view being put by Peter1469 - just for example. I agree with Jimmyz, that the mod team is pretty well balanced.
So, don't take this the wrong way, but maybe you need to provide a universally accepted definition of the noun liberal, before anyone can accept or reject your statement that only liberals get picked for mods or VIPs.