For me it's not that he doesn't push back, it's that he often interrupts with some trite nonsense. So the guest is getting in the details of something specific and interesting and Lex will interrupt with something he thinks is profound that's meaningless and derails the explanation. The questions he asks I find similarly frustrating - like he's not really listening, or thinking about it in any depth.

I get the sense he's constantly trying to prove how smart he is, and at least to me - it backfires badly. Hard to describe, but I guess it comes across mostly as shallow bullshit and it's tedious to listen to him despite his great guests.