Can someone simplify the 2nd and 3rd point (from top) of the post given in image below?

2 means the author thinks it's impossible to exclude politics entirely when creating something. (if your work aims for verisimilitude in it, your paradigm will influence it, so there is some merit in the claim)

3 is badly worded but can be restated: "It's disingenuous to link didactic stories to authors having interest in and responsibility for the message of their work."

I think they are trying to counter a theoretical argument that cites the existance of didactic works as proof that authors are responsible for their works' "messaging".

They might be trying to say something more along the lines of "Just because some authors preach doesn't mean every author must."

It's not a shining example of clear writing, though.