Stef I am not sure which statements you intend to have moral import. Here is how I am interpreting it, let me know where I am going wrong.
The statement "There are no unchosen positive obligations" has to be a moral statement, otherwise it doesn't make any sense. If it is not a moral statement then it means: unchosen positive obligations don't exist, which clearly is not true. An obligation to pay taxes is enforced against my choice. You could counter that I can refuse to pay taxes (and suffer the enforcement), but then you are just stating a tautology: "there are no positive obligations if you don't accept positive obligations" or more simply "there are no positive obligations if there are no positive obligation."
So I am starting from the premise that this is a moral statement. Moreover, it is a true moral statement as I will get to momently.
As I am interpreting your response, things like integrity don't have moral import. This makes sense as you explain in "Intro to Philosophy: Ethics, part 2 (theft argument): a positive moral obligation is nonsensical. In your example, if we propose theft as a moral imperative then we end up in an untenable situation where we are just constantly stealing back and forth, and if at any time we are not stealing (eating, telling other people to steal, debating morality, etc) then we are immoral. Likewise, telling the truth cannot be a moral imperative otherwise we would be obliged to constantly do nothing but tell the truth. Dissassociating from corrupt people cannot be a moral imperative otherwise we would be obliged to only associate with those who had the full complete truth, which none of us has.
Therefore I come to the conclusion that your message is "there are no positive moral obligations but you are generally better off following this program." This is what derives from my analysis above, but it sure seems like you are making a stronger claim than this. Also, this contradicts the refrain "Its not all about you." If the appeal is to making the reader better off (as Ash also asserts) then it is "all about you (the reader)."
What am I missing? I really appreciate your response.