Query (regarding projects, etc)

Right, I'm just vaguely annoyed right now, but I'm trying to work out if it's my fault for misunderstanding or the other person for miscommunicating:

My question is this: When asking whether someone can continue to help with a project, does an answer like "I'll come, but I'm not sure that I'll be able to help much" imply that the person will do what little they can, or does it imply that they are quitting? What would you take it to mean?

I would say that they are unable to help, but are willing to.

At least they show up.