God wrote the Ten Commandments, not Moses. He would not have been limited in any way by what Moses knew at the time. If his intent was that the Hebrews would ultimately read and write in Hebrew, why would it make any sense to write the Commandments in a language that would have no future relevance to his people?
No, why would they write in Paleo Hebrew during the David Kingdom and or in Proto Sinaitic script before that if the 10 commandments were etched by God in something else?
Because He wanted the people to be able to read and obey the text as it was written, at the time it was written. So, it would have to be in a language that was known to the Hebrews at the time the commandments were received.
By your argument, the commandments would not go into effect until Hebrew had been developed and some general literacy had been achieved, many centuries in the future. Even Moses would have been unable to read the commandments.
Following up what CurlyDave said to you, why would the Israelites be using a language like Proto Hebrew if God didnt use Proto Hebrew to etch the ten commandments?
Why would they be using Proto Sinaitic before that if God didnt use that for the Ten Commandments?
Why would God use a language to etch the Ten Commandments Moses didnt understand?
Nothing points to MT, Aramaic Hebrew, or even Paleo Hebrew being used for the Ten Commandments. But it points to God using the language people then could understand just like we have English translation Bibles and the Greek LXX being the dominant means of facilitating the scriptures long before that.