Correct answer: obtain legal counsel.
Simplified forum answer: the guidance only refers to business (and yes an individual operating for profit is seen as a "business") which are in the BUSINESS of exchanging virtual currency for real currency (or one virtual currency for another one).
So it really depends on what you mean by "Bitcoin business".
Are you planning on opening any exchange? Then yes you must register.
Are you panning on operating as a direct broker like coinbase? Then yes you must register.
Are you planning on selling goods or services for Bitcoins? Then no you do not need to register.
A company which sells widgets for Bitcoins is in the business of selling widgets for Bitcoins and thus isn't an "exchanger" per the guidance.
Yes, I do plan on obtaining legal counsel before actually starting up the business I have in mind. Just pondering some of the legal implications before doing so. Thanks though, your conclusions were pretty much the same as mine.
Interestingly, Coinbase seems to disagree with you about the requirements. They are not a money transmitter by their own admission:
https://coinbase.com/legal/user_agreement