That statement is demonstrably untrue.
Murder, rape, robbery, burglary, fraud are ALL morally wrong. Moreover, they violate some else's rights and are thus the fit subject of law. BTW, I consider abortion murder.
I personally find homosexual relations immoral. It's bad for the people who engage in it, in my opinion. But no one's rights are being violated. Thus it's NOT a fit subject of law.
There's no problem making absolute moral judgements holding to a libertarian philosophy.
I'm afraid there is. Libertarians do not call upon anything higher than the individual in their moral reasoning. That isn't good enough. Our laws much reference something higher than ourselves to be consistent. Otherwise what I believe is no better than what you believe. In addition, libertarians hold ot a Rights of Man argument that, in their reasoning, has nothing to back it up.