Aloth's endings involve him either becoming the head of the Leaden Key, or destroying it from within. That kind of seems like it would be a full-time job to do. How do you reckon they are going to justify him travelling half-way round the world to stop a living god? Also, if you are travelling with someone in such a position of power, wouldn't it render most of the challenges you face as meaningless, since Aloth could easily just command the Leaden Key to solve all the problems you face.
Also, if we are going to the Deadfire, does that mean that we can do what we want cause a pirate is free?, You are a pirate!