I'm sorry but the Bible speaks differently it says that the Law was given exclusively to Israel and proof that it wasn't binding to anyone but Israel is written down as no other nation was held accountable to it by the historical documentation in the Bible itself.
Micah 4:2 And many nations shall come, and say, Come, and let us go up to the mountain of the LORD, and to the house of the God of Jacob; and he will teach us of his ways, and we will walk in his paths: for the law shall go forth of Zion, and the word of the LORD from Jerusalem.
I don't understand why you keep viewing the law of God with the point of view of "being accountable to it". The law of God was revealed so we would know we're in sin's grasp. Anything God did was for benefit. You say He only gave it to Israel, but there was no command by God that Israel had monopoly of it. Again,
the purpose of God writing His law down was to identify sin in Israel, because they were to be a nation of priests, ergo, pure. How is "knowing when we sin" something monopolized by one nation? By the way, once you are aware of the 10C, your conscience is already bound to it. It's simple - you can't say you don't know it. Therefore, you are accountable to it because its sole purpose is to point out when sin happens.
Gentiles in the Bible in the New Testament were not subjected to the Law either and the council of Jerusalem itself attests that that.
Actually, almost all those laws they brought up at that council were all pre-Sinai. Circumcision was given via Abraham. Blood ("meat juice" more accurately) restriction was given via Noah. Abstaining from food offered to idols was not given by God anywhere in the Old Testament. As for "the law of Moses", that was a broad term meaning everything in Exodus-Deuteronomy, including what to do after [bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse][bless and do not curse], after having a period, how to identify different types of skin lesions, how to treat slaves, rules about incest and bestiality, etc. While the council didn't go into making a distinction between the laws in the law of Moses, it is clear the apostles considered differences. Most famously quoted,
"the royal law of love" which Paul and James specifically advocated,
is part of the law of Moses.
I'm glad you admit that those who don't know the law get judged differently that concludes that the Law is truly NOT the arbiter of sin because if it was then ALL would be treated the same by the Law knowing it or NOT.
En contrare, the Law is what God uses to judge whether there has been transgression - what is different is "the extent of guilt". It is the same way today with murder. There are different classifications in most countries' laws about murder.
It would be like breaking the speed limit without knowing the speed limit - the police officer can take that into account in determining whether you get away with a warning or get ticketed. Did you break the law by speeding above the speed limit? YES. Did you know about that particular speed limit? No. Are you still guilty of breaking the speed limit? Yes. Is your punishment as severe as if you had actually known about it? No.