"...tickets which the airlines have offered to sell to people traveling from point A to point B, and under terms which expressly prohibit jumping off at point C. "

That wasn't true in Australia for Unknown, and I doubt it is true anywhere.

Think of how impractical it would be. People have plans, but plans change. People miss flights. They get sick. They're hit by a bus. They just change their minds. So they'd all be opening themselves to litigation? That's not why people get on a plane.

" Terms that you generally have to check a box saying you're agreeing to."

See Lumifer's discussion of contracts, presumably in Common Law jurisdictions: http://lesswrong.com/lw/lne/how_to_save_a_lot_of_money_on_flying/bxo2

Non negotiated contracts are just not treated the same as negotiated contracts.

"In any event, my other point still stands: telling other people how to exploit anti-inductive loopholes is a dumb idea"

In most cases, no. I'm often struck by the cheek of people telling other people how stupid they are in the pursuit of their own values.

You're just making false assumptions about the values that people have. People often share information on tactical advantages that become marginally less advantageous the more other people know about them. They're not all stupid - they're generally just obtaining some value other than the value that comes from exercising the advantage when they communicate the advantage.

"you do not talk about anti-inductive loophole club, unless you stand to profit more from its promotion and eventual replacement than you do from the loophole itself"

No. Still wrong. You best decision is not determined by the worst case macro state on the loophole. People share deals primarily because they want to help other deal seekers win too. For many, that's a value.