You're 100% correct when you say that changing venues and having the arguing parties work together had changed the tone and flow of the debate experience but I can't agree that changing context will ultimately improve an argument. I would like to discuss some things I believe to be at play here, but not mentioned.
The difference between arguing online and arguing in person can be of significant importance to how the two parties interact (argue). I will go ahead and propose that if the two parties had instantly (after your request to speak in person) transported them selves to a room and sat right in front of each other without the cookies or you even being present, even then their tone and ferocity would change from what it was online. I believe that when we are online we are no longer bound by the effects of communication between body and mind (similarly time depending on the online medium). When we are online we do not read the body language of those we are speaking with and we all know that body language makes up for a very large portion of how communication plays out.
When the two parties are instantaneously transported from their chairs to being right in front of each other they are subjected to a larger portion of their emotional consciousness then they were online. Their expectations of people and how they communicate in person becomes in affect. Those attributes of the arguing parties personalities weren't all at play when the conversation was happening online.
Their characteristics while the argument was online could even be considered as dissociative to their true personality traits. Which means, yes... Changing context will effect arguments, but I wouldn't go so far as to say it will improve one. Who knows... Maybe one of your guests had a sexual desire for cookies and so became aroused which made them care less about the topic being argued and so didn't fight back as hard as they might have online.
I see a major flaw here that I have to point out.
The pitch to the publishers was absolutely a fabrication of true readership of the fan fiction, that is fair call. But to say that any book with the same amount of marketing would reach the same level of appeal is short sighted.
Simply, the book had the X-factor. The story was provocative, sensual, shocking and ultimately all elements contributed to it's appeal. People talked after it was published, people talked about how it effected them and that raised awareness with the millions of people who were ultimately affected (some of which have never actually read the story, like myself). I live in Australia and from my perspective the book was never marketed as "read by millions online first as a fan fiction and now published as a big, rock-hard book".
It was the content of the story and how that resonated within society which ultimately lead to it being so huge. The X-Factor, you see it in all facets of the entertainment industry niches (I know I work in the industry). You may even find that if 50 shades of gray were released 10 years ago that it would never have gained such acclaim at all because we as a society may not have been so engaged with it's content.
I would first like to point out that your lack of understanding in what various religions view as "god" is hindering your ability to answer the question. However it's not your fault as most major religious devotees don't understand the esoteric nature of the very religion they believe in and it's certainly not expressed to people who do not follow said religion.
Firstly the exoteric understanding of the christian god has very little to do with the creation of the universe but has more to do with the design and implementation of morals, ethics and general laws for the society and planet we live in.
The Freemasons and Hindus have a good understanding on what it (god) might be, they refer to it as the Grand Geomatrician (that giant G in the middle of the square and compass) or the Grand Architect, and for the Hindus; Brahma, (who's dream we are living inside of) accompanied by his two pals Vishnu & Shiva (who are forms of Brahma himself within his dream). This is the being; beings or forces, or whatever it is that has the freedom to imagine and has designed the universe and it's laws that we exist in. Which is eternally the same principle as a super intelligent AI creating a simulation.
Whether or not we can communicate with whatever it might be comes down to how we as a consciousness can interact with the design and laws of the universe (and what is consciousness and does a soul exist?) . Like "The Sims" are our actions merely driven by the intentions of a programmer or a being in control of us? Or like "The Matrix" do we have the ability to freely interact with the code itself. If the answer is the latter then yes I believe we can interact somehow with the creator force, however if it is the former then we do not.
p.s Those of you who believe that the super intelligent AI simulation is probable, however don't believe that a creator "god" for our own universe is just as probable are naive.