Ok, let's look at it from your perspective,
Isaiah 9:6 (KJV) 6 For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.
The KJV says, "THE mighty God", not 'A' mighty God, not just "mighty God" as you have quoted, but, "THE" mighty God.
And, since Isaiah 44:6 says, "besides me there is "NO" God". Why would God want to deceive people into calling Jesus, "THE" mighty "GOD"? And it is worse, telling people His name will be called, "THE" mighty "GOD" when He wasn't even a God at all. God says, "He's not going to be a God cuz I'm the only God, but I'll have people call Him, "THE" mighty "GOD" just for laughs and giggles".
Isaiah 44:6 (KJV) 6 Thus saith the Lord the King of Israel, and his redeemer the Lord of hosts; I am the first, and I am the last; and beside me there is no God.