Ignoring all of that for a second can we just appreciate how lucky we are reinforcements are coming? We're fucked to hell no matter what we choose unless the fight rolls are like, 98 to 2 in our favor. Same for any diplomacy roll too.
Now onto the topic on hand.
Here's the thing. That's relying on the Kadabra to be a very stupid Kadabra. It has a job. To erase memories. And if it's owner learns it refused to do so because it didn't like the Grunt, well, who knows what punishment it'll get?
Problem with spooking it, and whilst I doubt being able to let's say we do, is that it might do a rash action and blasting us and our Pokémon with Psychic. It's not an exaggeration to say this thing will likely one shot us. It's two and two thirds ranks higher than Fang. Another whole rank on top of that over Maelstorm. I'm more comfortable being attacked by a calm psychic type than a panicked one.
If this quest has even a drop of reality influencing it, talking is not a free action, and it may not care about what we're babbling about and capture us in mid speech.