Duke Leto firmly intended to train the Fremen into an army to fight the Harkonnen, and, possibly use them to put the Atreides on the Lion Throne at some point down the line.

Righting the wrongs the Fremen have known was always a distant second priority at best (he most certainly never intended to help them take back control of the planet).

At this point in the book and the movie, this is also roughly where Paul's mind is at. He wants to use the Fremen to survive the fall of House Atreides, avenge Father Dear and possibly become Emperor. He's also extremely worried about escaping his vision of a galaxy-wide jihad.

It takes him a while to actually "go Native" and count himself as a Fremen.