If I get your drift, there is no standing to sue on the signature requirement either. If there is, what is the difference between the issues (petition signatures, vs. qualifications)?
I dunno about the signature requirement. Most of the obama birth lawsuits were thrown out for standing from what I recall.
You and I cannot challenge their qualifications unless we are running for the same office.
Probably a good thing overall as it would allow activists to clog the courts. A bad thing in some cases.