An echo chamber is a place where the local acoustics make it difficult to speak clearly.

Medical science is able to speak with brilliant clarity hard-earned from centuries of experimentation on the topic of heart disease.

If I hear a discourse involving a cardiologist and a layperson, and it's not really made apparent who is the expert and who is not, then I call that an echo chamber.

That's not the conventional definition of a metaphorical echo chamber.

> an environment in which a person encounters only beliefs or opinions that coincide with their own, so that their existing views are reinforced and alternative ideas are not considered

Source: https://www.lexico.com/en/definition/echo_chamber

He has said it time and again, that he is willing to sit down and have a reasonable conversation with anyone and everyone.

which is a silly position to take because putting quacks and experts into a room on topics that require domain knowledge and scientific expertise is counter-productive and gives a false impression that both opinions are equally valuable or justified.

In reality, the show is an excellent avenue to mainstream conspiracy theorists and people who want to sell their latest books or products or whatever, and the people who will listen to it will get a hugely distorted view of what the actual consensus on certain topics is.

This is the same sort of dynamic that recently cropped up around a certain youtube 'educator' who claimed to teach people ML and to have disrupted the cartel of higher education, only to turn out that he had plagiarized a lot of his content and that the education was actually of extremely low quality. The same mentality, gatekeepers are evil, listen to the pot-smoking show-host who brings you the real information that they don't want you to know, yada yada.

Having guests with opposing views doesn't make it less of an echo chamber when the host is totally biased towards one of the opposing viewpoints.