Right of personal choice to live your life as you wish as long as you do not infringe another's rights of personal choice is the tenet here. Being gay, consensually, does not infringe another human or animal's rights. Bestiality infringes an animal's rights. Rape infringes another human beings rights. Paedophilia infringes the rights of a child. Murder infringes the rights of another human being. Theft infringes the rights of another human being.
You say right of choice leads to a 'free for all', by which I assume you mean social chaos, without law. In fact, equal rights leads to exactly the opposite; social equilibrium, the freedom of rights for each individual, regardless of race, religion, gender, sexual orientation or sex.
Again, the taking up of a religious life, with all its personal laws, is a choice undertaken by the individual, but it is not the legal obligation of all individuals to take up a religious life, with all its personal laws. A person's secularly legal obligation is to abide by secular law, which by definition is not affiliated with, prescriptive of, or biased towards any religious or non religious worldview.
Secular legislation is the practice of creating inclusive laws that are not based upon religious tenets but upon the premise of equal treatment for all people. The law recognizes the authority of no religion or belief system other than the law itself, and the laws themselves are based upon nothing more than this principle: equality of rights. That equality of rights is the same for EVERYONE. You might disagree with some of the consequences of that equality of rights, and that's your prerogative, but you are also bound by them, JUST LIKE EVERYONE ELSE.
The law does not prohibit you from taking up a personal religion, but it does prohibit you from enforcing your personal religious laws (which stand outside secular laws) on others. Nobody says you have to be gay. Nobody says to have to be straight either. Why? Cause being gay or straight is a personal choice undertaken by the individual that does not infringe another's right to personal choice.
However, the law says you can't be a rapist. Why? Because rape is a personal choice that directly violates the rights of another person to personal choice.