Was there any mention of the jet elsewhere, e.g. in some printed t&c? If it was only in a random tv ad, then I side with Pepsico too. And I wish I had a spare 700k for a random stunt like this.
The guy didn't have that much either: "Leonard […] convinced five investors to lend him a total of $700,000".
They thought they had a case since Pepsi “forgot” to put a fine-print disclaimer at the bottom like most other commercials.