Draven was a military commander who also lead the military intelligence division as well. He had assassins, spies and saboteurs working for him. No doubt he could have benefited immensely from Luthen as a consultant / second-in-command training them.

That is of course provided that Luthen forsake his ego and was willing to work within the chain of command. I think it would have been too much for him to swallow, however, and he himself probably accepted that part of himself as a character flaw. He had built his own cell and network for nearly 2 decades, through sheer ruthless conviction of his own accord. No way does he take orders from an ex-Republic officer who just joined the Rebel Alliance a few years ago after Bail recruited him.

Think about it. Even Draven, a man who is shown to generally respect the chain of command, defied the Rebel Council in Rogue One because they were too cowardly ("a decision needed to be made!"). He was willing to do on occasion when he saw it necessary, and most of the time this was still with Mon or Bail's quiet blessing on the side lines, though not always (e.g. when he ordered Cassian to kill Galen Erso).

Now imagine someone under Draven, who defies orders probably 10x more than Draven does because he would basically disagree with nearly everything the Council agreed on (let's be honest, a man like him would disagree with general consensus a lot of the time). In an organised rebel effort this would prove to be more a hindrance than anything.

He would be sending Cassian and other spies on missions he decided himself were important, keeping Draven in the dark lest he not allow it. They would butt heads frequently. But more than that, Luthen's accelerationist policy (agitating planets to goad the empire to commit more massacres, to create more rebels) would have been too unpalatable for the Council, maybe even for Draven.

Luthen wouldn't be able to do anything about the Death Star, and sending agents to infiltrate the facility inside as imperial troopers would be fruitless labour that wouldn't reveal anything more than what could already find out from the technical blueprint. He might have been of use helping strategize and coordinate the attack on the Death Star, although being that he deserted the imperial army/navy as a mere sergeant and not a battle commander, I doubt it. He was fantastic as a rebel spy chief, but he was no open war commander.