That sentence can be taken out of context and misconstrued, I guess, depending on one's slant. Gays will have the same rights to contract between themselves any way they see fit just as any other Americans can enter into contractual relations. It's none of our business what type of civil union relationship they contract for between themselves. It should be a private business matter. If it needs to be codified that it is legitimate, that's fine. I don't care and I don't want to know what they agree to between themselves.
Romney has always supported equal rights for all Americans, but has specifically opposed special rights for gays --- especially anything that would change the 2000+ year old definition of marriage just for them.