Yes. Absolutely, that would be a challenge. You don't want a podcast to devolve into something ugly because you had to seek out someone who you couldn't "vet" appropriately before hand. It's certainly not an easy solution to do in a timely fashion, and I get that.
At least from my end, your efforts to give the Shalladin arguments a fair shake are appreciated. However regardless of good intentions, arguments made for a viewpoint you don't share will usually fall short (something I always struggled with when required in debate to take such viewpoints counter to my own beliefs).
Hopefully I'll find some time in the near future to give it another listen, take notes, and come up with points I can concede and others to rebut.
Otherwise, well produced podcast, thanks for getting it out there, and thanks for putting up with us over in the "thread that won't die" (you know the one )