It seems to me that if a 03 FFL holder buys, say, a case of rifles with the INTENT of picking the best to keep and selling the rest, he is a dealer, not a collector. He doesn't need to INTEND to sell some specific rifle or rifles, he buys with the INTENT of selling, which is the definition of being in business.
In case it has escaped notice, the antis have been pushing for years to end the C&R category and the C&R license, claiming that 03 FFL holders do not keep proper books, do not perform NICS checks, and are a major source of crime guns. While I know of no evidence to back the latter claim, if they make it often enough (like the "gun show loophole") Congress will believe it.
Basically, if collectors lose the 03 license, it will be due to those greedy and irresponsible people who want to sell guns and make money without getting the proper license and going in business right.