I tend to agree with you. The main purpose of writing that part of the post was to stress the fact that we are aware of such a potential concern and would rather discuss it early rather than later.
Also, it may very well be that the different members, although working together in the SBA, have very different opinions on the ideal direction of Steem as a whole. So that even if the joint stake of the SBA members would eventually grow large, it wouldn't imply that witness votes would be centralized.
In any case, I am happy to have that discussion, especially now when we're also forming a foundation for Steem.
Yes, absolutely agree. The important thing is to have this discussion early, provide transparency and take on board input from the community