Maimonides codified the laws for non-Jews already a thousand years ago
Then I say: what does the Torah say? Torah predates Maimonides by a huge margin. Age old debate of laws of man versus the Torah.
The Tanakh says the exact opposite:
So says the Lord, "Keep justice and practice righteousness, for My salvation is near to come, and My benevolence to be revealed."
Happy is the man who does this, The man who will hold fast to it: he who keeps the Sabbath from profaning it and guards his hand from doing any evil.
Let not the foreigner who joined the Lord, say, "The Lord will surely separate me from His people," and let not the eunuch say, "Behold, I am a dry tree."
For so says the Lord to the eunuchs who will keep My Sabbaths and will choose what I desire and hold fast to My covenant,
"I will give them in My house and in My walls a place and a name, better than sons and daughters; an everlasting name I will give him, which will not be discontinued.
And the foreigners who join with the Lord to serve Him and to love the name of the Lord, to be His servants, everyone who observes the Sabbath from profaning it and who holds fast to My covenant.
I will bring them to My holy mount, and I will cause them to rejoice in My house of prayer, their burnt offerings and their sacrifices shall be acceptable upon My altar, for My house shall be called a house of prayer for all peoples.
So says the Lord God, Who gathers in the dispersed of Israel, I will yet gather others to him, together with his gathered ones.
Isaiah 56.1-8 JPS and Chabad has it here.
Anyone who keeps His Sabbath and His Commandments. Very plain. There's no two instruction sets. But it's okay, I went by the whole thing for a long time and I just needed to read for myself as I learned I can't take anything for granted.
This also doesn't negate everything else Maimonides wrote. We can't get lazy and just have someone else do it for us because we're commanded to read the written word every seven years. I'm sorry, I'm very opinionated on this topic.
Maimonides’ writings are quintessential Torah observance. What can I do on a Friday morning, with kids on school vacation running around like banshees, a bit of contract work to complete, and 2 meals for 14 people each for Shabbos to prepare.... What can I do to convince you that Maimonides, a fine pharisse, like all current day orthodox Jews, keeps 100% of the actual Law of Moses, exactly as G-d intended, (even without our Temple, temporarily, as He intended that too...) and that your interpretation or rendering of the text, even from a Chabad website, means nothing?
No offense.
Jews,have a great Shabbos! Gentiles, embrace your Creator the G-d of Israel! He gave you seven ways to connect to Him and they enlighten the eyes and make live fulfilling (not to mention eternal.)