Like so many other posts, this falls into the “he sees only what he wants to see”. No reasonable reading of the address, the surrounding correspondence, or reporting from the time would come to the conclusion that Lincoln “supported”, advocated”, or “pushed” the amendment. His stated position was neutral.
It’s such a silly argument, and really only serves to illustrate a non-serious person.
Lincoln did not believe the Corwin amendment was necessary. He believed that the Constitution, as written and interpreted, was sufficient protect slavery in the states where the institution was legal.