Official FAA position on 'Furtherance of business'?

One CFI I talked to said basically that he thinks that the FAA expects
*precisely* that. The that limitation precludes the exercise of the certificate
for *any* flight where there is a reasonable expectation
that business may be furthered as any result of that flight.

Sheesh . . .

Take-off, fly, and land, and that's the end of the FAAs jurisdiction. If you
then conduct business at your destination it's none of their concern. That
business has nothing to do with the conveyance that got you there.

You don't sign away your rights as an American citizen just because of some
ticket the feds issue . . .

Nick