I'll put it this way to see if you and @Tha_Mac can see where I'm coming from:
Snitching is a huge 'no no', you're not even supposed to snitch on your adversary. You can't walk into a police station and tell on your enemies. That's against the code, that's not acceptable on the streets. However, you absolutely CAN set your enemies up (be it with other gangsters or with the police, or the IRS, their family, etc). That's all fair game.
What makes this situation foul is that Ghost did this to someone he's supposed to be cool with. So it's fukked up, it's dishonorable, but it ain't snitching.
I see that point of view but if you Ghost and Tasha trying to set somebody up why not just rob and kill Kanan? Instead of busting out his tail light, him going to jail with him possibly figuring out somebody set him up and coming back looking for revenge like he doing now.
Setting him up to go to jail leaves the avenue of him accusing Ghost and Tasha of his situation where if they killed him Ghost take over his business is the top dog and don't have to worry about Kanan coming back at them. Maybe some loyal soldiers but they soldiers and not bosses for a reason.