I've reconsidered this situation. In the future, when I find a sig that violates Site Rules, I'm just going to replace it with this text from the Site Rules, without warning:
M. Signatures: Your entire sig must not be larger than 150 pixels high by 600 pixels wide in total, with all graphics and text included. Total graphics in a sig may not exceed 500 Kb.
Future violations by the same person will result in that person being added to the "no graphics" user group, which will make them unable to have a sig.
There is no favoritism here. If someone's sig violates Site Rules, it's because I haven't seen it.
What ever happned to this? I see a few sigs that are breaking the rules.