Nice post. I'm glad that the conversation is continuing. Both PMI and Agile people need this dialogue.
A couple of comments on your post.
1. I agree that Agile Advocates need to learn to speak to the business people. However,
2. Agile adoption has been fast in many places, not slow.
It is true that many Agile Advocates (AAs as you call them -- like the analogy BTW, and think it fits! :) don't talk "business-ese". That's been a failure of the community, however that is far, very far from being a problem in adoption. Having been involved in two major organization change projects I can vouch for the lack of business-oriented communication, but I can also assure you that speed of adoption has been anything but slow. I know of a company that has several 10's of thousands of employees where Agile is a topic of discussion at all levels, from top management to the team level. This is very encouraging, especially because this company has not been shy in removing some of the building blocks that are in PMBOK (and inadequate to software development) and build new processes at all levels based on the principles of Agile Software Development.
3. Agile software development needs discipline
I agree with this, but the lack of discipline existed in software organizations when PMBOK was the prevailing framework for organizing projects. Lack of discipline is a problem that Agile encoutered when it started, not a problem created by adopting Agile software development methods. Indeed, it is my experience that agile software development builds a much higher level of discipline into the development process than was previously the norm.
4. Agile alignment with business objectives.
This is a topic for a post in itself, but I'll just refer one example of how agile brings focus and alignment with business goals. Check this post by Dean Leffingwell where he explains how requirements management in Agile can be done in a way that directly reflects the strategy of the company.
Let's continue the dialogue. I've learned a lot and hope to continue learning from it! :)