I am not a lawyer and can only provide an educated guess into the differences of the complaints.
The first complaint had many deficiencies because it was too broad e.g. trying to prove state level election fraud . The complaint should have had one objective from the start, to present a Federal Question as it pertains to the law that the lawyer is trying to invoke. That law being 11 CFR § 100.2(e) that defines a national convention as a "Federal Election" and 42 USC § 1971(b) of the Voting Rights Act (VRA)that addresses the binding of delegates. The Second Amended Complaint does just that.
The Federal Question presented is whether the VRA applies to the National Convention of the Defendants to be held in Tampa commencing August 27, 2012.
If the Judge finds that the VRA applies, delegates are unbound. If not, we proceed with RNC rules (keep in mind that the RNC may not recognize binding anyway).
11 CFR 100.2(e)- Caucus or Convention. A caucus or convention of a political party is an election if the caucus or convention has the authority to select a nominee for federal office on behalf of that party.
42 USC § 1971(b) Intimidation, threats, or coercion
No person, whether acting under color of law or otherwise, shall intimidate, threaten, coerce, or attempt to intimidate, threaten, or coerce any other person for the purpose of interfering with the right of such other person to vote or to vote as he may choose, or of causing such other person to vote for, or not to vote for, any candidate for the office of President, Vice President, presidential elector, Member of the Senate, or Member of the House of Representatives, Delegates or Commissioners from the Territories or possessions, at any general, special, or primary election held solely or in part for the purpose of selecting or electing any such candidate.