Moses grew up in Egypt. The Jews were in Egypt for generations, as servants/slaves of the Egyptians. They necessarily spoke and wrote Egyptian, whatever else they might have spoken among themselves.
But, but, but, MT has to be on the two tablets, it just has to be! Or maybe it’s Aramaic Hebrew?
Nah, it’s NIV, NASB, or KJV - or NKJV. Unless it’s 1611 KJV.