So the further away the country and laws go from Judaism the better because it is so clear one is water and one is oil. If the laws of the country are the same as the torah it could be very confusing...
This law was a welcome one I guess.
(As aside note someone pointed out that married couples have less relations than single people so this is also a good law because there will be less total immoral acts happening in the country.)
Theoretically you would be correct, but in actuality that is just not the case for two reasons:
1. While Jews don't need the government to make civil law match that of the Torah's, the Torah does dictate that there are certain laws that are universal and critical to make society sustainable. Sexual immorality, which includes homosexuality, is included among these. (Of the seven universal laws, not all are of immediate destruction to society. Sexual immorality, as brought down in several places, IS among those critical to society.)
(A brief quote from congress:
"Whereas Congress recognizes the historical tradition of ethical values and principles which are the basis of civilized society and upon which our great Nation was founded; Whereas these ethical values and principles have been the bedrock of society from the dawn of civilization, when they were known as the Seven Noahide Laws")
2. Outside influence DOES have an affect on the Jewish people. There is a reason the Alter Rebbe (Ba'al Hatanya) sided with the Czar. While Jews have absolutely no control over how gentiles behave, the more immorality that exists, the more it creeps in. When the government declares immorality the law of the land, it creeps in ever more so.