To figure out usually means to find out.....although on Dictionary.com, it's defined as "hard to understand or solve" with none of its definition close to "to find out". What puzzles me more is the example it gives for the meaning "hard to understand or solve is "we couldn't figure out where all the money had gone." (Obviously, neither of these meanings apply here; solve is close)
So if "inscrutable" does mean hard to figure out. It will be hard to understand, which conform with all of its other meanings. It would be weird to see it mean "hard to find out."