There's a difference being unable and powerless to do something and coming across as if you just don't care. Saying that you're just doing your job and not attempting (or even pretending) to do something about it it comes across as the latter and a major turnoff to both your customers and business partners.

In this case it sounds like this company was asking Godin for a favor - sure you could call it a rant, but it's also pretty fair given that it's not like he went to them, they went to him (which would make the attitude especially galling).

When you start saying stuff like 'it's not my department' when you're asking for a favor from someone else, it's also saying that you have little to no pride about the company that you work for and I think that's his point. If you care so little, life's short. Why wouldn't you find somewhere better to work (or better yet, start your own business that you can be proud of)?