They were worried that one particular player’s character would end up allying with the slaver, selling the rest of their party into slavery and going into business with the evil salamander. Naturally, they didn’t want that to happen.
I’m like “sounds awesome.”
I love egging my players on and having them get into situations where I have genuinely no earthly clue what they’ll do. Last night, my players fought a particularly nasty bad guy. He’d even killed a PC during the fight by hitting her while she was already down (she was brought back with revivify, don’t worry). So, of course, they hate him. And when the outcome of the fight was inevitable, he surrendered, casting aside his weapon. The players did technically start the fight, so one character wants to talk. Another walks up and casts burning hands at his eyeballs. The end.
Now, I had no idea what the players would do in that moment. I was walking into a spot where my players could have done literally anything with the guy and I would have had to adapt, both with roleplay and story. I had no idea what was going to happen.
And having no idea what’s going to happen is the best part of being a DM.
Now get out there and tell a story!