He is concerned that AIs might not be conscious. Interestingly, this is IIRC the exact opposite fear to Eliezer, who is afraid that they might be (though I may be misremembering). I think Tegmark is mainly talking about UFAIs that replace us (rather than FAIs that protect us) - so basically he's saying he'd value a conscious clippy, but not an unconscious one.
Does he define "conscious"?
Max Tegmark, from the Massachusetts Institute of Technology and the Foundational Questions Institute (FQXi), presents a cosmic perspective on the future of life, covering our increasing scientific knowledge, the cosmic background radiation, the ultimate fate of the universe, and what we need to do to ensure the human race's survival and flourishing in the short and long term. He's strongly into the importance of xrisk reduction.