That is to say, the Leatherette Tortoise quest line is weirdly bugged. It is my fault! (of course!) but I am unsure of how to get a workaround going, looking into it, that will retroactively apply. It should be fixed going forward--probably--I think. (Basically a variable was set wrong so if you were sorry for killing the Tortoise, the Tortoise could show up again. Which is a nice thought, but unrealistic.)
So...um...we will fix it in the next version.
(Why did a weird shudder go down my spine when I said that? As if a thousand game designers gave a short bark of humorless laughter and then dropped their heads into their hands and wept?)