Piers didn't get demolished exactly. He allowed Fuentes to make his point, he was somewhat cordial despite clearly hating Fuentes. Very British actually.

The audience that watches Piers had their beliefs confirmed and Fuentes did make his points well enough except for not being gay part.

The part where Fuentes asked, why is it to soon? was incredibly funny. I'm also glad Fuentes did get that monologue in uninterrupted about genocide. That was a point Piers did not engage or he would have lost. Clearly Piers set up the interview in an attempt to "de-radicalize" Fuentes viewers so any pushback against the idea of genocide would have lost any hope in reaching his goal audience.