They addressed the issue somewhat with Draven mentioning that Rebel policy will soon change to monitor who leaves and who doesn't but considering how paranoid Luthen and Draven have been shown to be in other episodes/works, I'm surprised that there wasn't more fuss from the Rebel side about Bix, who knows way too much, running off without any way to contact her. She knows where Yavin is. She knows enough about Luthen to ensure Luthen and Kleya get sent to the spice mines of Kessel. She hasn't been mentally stable since her torture and now has a history of drug usage.
For all the Rebels know, she's going to sell them all out for hefty financial reward once she hooks up with someone who looks like Jason Momoa, a massive improvement over her ex-boyfriend Cassian.