I don't think your following me here. The shout was YOYD, you asked for something that went against that, and he said yes (this is a concession as it broke the pre-established rule, the very same rule you are arguing that would've prevented you from making the deal in the first place). The deal, from what I read, was that they removed the YOYD rule from one specific item, that item being the Tongue. Not that it matters, but you didn't make mention of the shank in your line about the tell you sent him. I am led to believe that the deal you made to allow the exception to the YOYD pre-established rule regarding the Tongue was agreed upon under the condition that the same be done for the Shank, thus adding another exception to the rule (the shank). Meaning, had the shank dropped on one of their orbs, you would've been able to lot it as well.
As you didn't ask specifically whether or not you would be the only one allowed to lot the Tongue (regardless of whether other people could lot the shank) before-hand, what occurred was in no-way his fault. He said what he meant, you made an assumption. In the end, you didn't lose anything, other than the time it took to do the first two runs, you should consider yourself lucky for not losing anything during such a misunderstanding. Next time, ask for specific clarification before joining. Think of it as common courtesy toward yourself. (Common courtesy doesn't fall under the jurisdiction of the person you are making the deal with to make absolutely sure you know what said deal is, if not asked for clarification, which tbh in this case, he did when he said "chance to lot".)
Edit: You also tried to change the deal right before your orb, which honestly, is pretty rude and no one would ever agree to that. If anything, you were the one trying to break the deal, AFTER they had used their orbs, which, let's face it, is the exact opposite of common courtesy.