@Goldfish it might be a good idea to add in something that explains the actions of the OGs. The guy's obviously been around the block more than a few times and giving the mysterious stranger a motive would probably put him more at ease than any reassurances we could give.
Also, what is our long-term plan here? I was under the impression that we'd have him publically convert, and in return we'd be growing a bunch of vegetation/a heart tree. One obviously that isn't sacrificed with the Toad Idol, and since it was done by 'Dywen' the Illithid won't know it was us anyway.