Applejack lassoed the Cider Barrel away because flim and flam made that cider with apples that belonged to the Apples without paying the apples for the Apples.

AJ agreed to give some for the demonstration. She didn't agree to let them sell it and pocket the money.

Furthermore: The quality of Cider is determined by the quality of the apples. The cider-Squeezy made good Cider because the Apples grew good cider-apples. Note that the cider was inedible after they turned off the quality control.

And also note that they basically stole half an orchard's worth of apples from the apples and destroyed many of the trees becuase they didn't pay for the apples/trees and the cider made ended up inedible.

Flim and Flam aren't a criticism of Big Business. They're con artists and scammers who show up whenever a con artist or scammer is needed. Them and Iron Will, but Iron Will is at least honest enough to cut his losses when he's been had.

Note how Rarity, The Cakes, AJ's Farm, and countless other honest run businesses are depicted as being profitable, at least enough to stay open. Even Filthy Rich is, in the main timeline at least(EQGs is more ambigous) as having made his money in honest deals and givng producers a fair cut.

The show ain't critical of business. IT's critical of unethical business practices.