However, I disagree with his idea that people dying all for the sake of progress is alright.
Ah, but that wasn't his position, really. He thought those deaths on the Pegasus were a tragedy, just like anyone else. Pressman's rationale was that they were mutineers, & that their deaths were a direct result of trying to shut down the cloak, once he'd been driven from the ship
He was wrong, but not immoral. He was violating Starfleet policy, but he & I'm certain many others thought they were acting in the best interest of the Federation, & in reality there would be a long & ugly trial, that reached up into the ranks of the highest in Stafleet command, with the Romulans watching the whole thing. Riker would be replaced during it, & quite possibly be reassigned, even if he was exonerated. It is realistic though that Picard could fill the XO position from within, & then offer it back to Will, when the time came
But honestly, Picard's decision would yield very precarious results, because many would see him now as a whistle blower, & less loyal to Starfleet, than to his own ideologies. He revealed the treaty violation to the Romulans, who had their own Phase Cloak disaster only two years earlier.
The official policy would likely be for Picard to arrest Pressman & Riker, without revealing anything to the Romulans, which probably would have resulted in another cover-up.That is why Picard exposed it, but in doing so he has further jeopardized Romulan relations. Realistically, Picard would be looked upon differently by many in Starfleet