I have no idea. Probably with the right judge. Do you think he decided not to challenge simply because he wanted to be nice?
With 5000 signature to choose from, I think you can pretty much guarantee that he would have been able to find at least one that could be disqualified. Ironically this happened as the Illinois GOP was being investigated for using state workers on state time to challenge the signatures for Libertarian candidates.
Do you think he decided not to challenge simply because he wanted to be nice?
To be nice? No. He claims the reason is that the voters should be able to vote for the candidate of their choice. If you want a more cynical reason, you could point to the negative publicity for the LP that would have resulted if Bush had actually been disqualified for the ballot in a major state.