Why is Elohim plural and what does it signify about the Trinity?

Les teaches that in Genesis 1 the God of that chapter is known in the Hebrew as Elohim, and he equates Elohim with the Trinity of God the Father, God the Son, and God the Holy Spirit. Elohim is a plural word in the Hebrew, so it had to be plural to envelop all three persons of the Godhead. As the narrative moves into chapter 2, the term is no longer just God but becomes Lord God, all capitalized, still Elohim, and now identified as Jehovah, who is God the Son. Les explains this is purposeful: after the restoration of creation and man has come in to fill the scene, God knows there will have to be a plan of redemption, and not only a plan of redemption, but a person of the Godhead who could continue to communicate with His created beings. This connects to John's Gospel, where the Word was with God, was God, and became flesh.