Agreed. And as the end of the movie tells us they apparently did get into show business again and made a crap load of money.

Rewatch the scene with Goodwin and the Geritol Prez (played by Martin Scorcese); it explains it all there. If Enright and Co. would have implicated the network, they'd never find a job in TV again. Sure, the public would forgive them, but what would that matter?
As the Geritol head says in that fateful scene, the public has a short memory but corporations never forget. Better to piss off the public for a little while than be blacklisted by corporations forever.

It was easier (or nobler, etc) to present themselves as lambs to the slaughter. Dont recall the details on Al Freedman but Enright & Barry did recover, and although it took a while, resume their careers in television. To implicate NBC and Geritol in the rigging would have permanently marked them and mucked up everything to beat the band. In the end it was about power and deep pockets.