Exegesis of Hebrews 11:6

Polycarp engages in a little exegesis of Hebrews 11:6 in his blog The Church of Jesus Christ. He argues that the εστιν of verse 6 should be translated as "he is the I AM." I do not find the translation particularly convincing. I think that if the author of Hebrews wanted to allude to Exodus 3:14 he would have used the first person singular ειμι to make the allusion more apparent.