I don't know that snitches 'deserve' stitches, per se.
I think, for many, it comes down to them or the other guy. And both sides know the risks of what they are doing. The snitch knows they can be caught and punished for snitching and the dealers know they can be snitched on and sent up a creek.
For me, I would need to feel that 'snitching' is ethically justifiable. Not just to save my own skin, but to stop a real problem, a real threat. I wouldn't necessarily be okay with snitching to the cops as I don't believe in caging life, but I have let slip to the right ears, here and there, throughout the years, when someone is doing some fucked up shit.
I won't get into details, but it really comes down to the intention behind the snitchng and the principles of the snitch. It also comes down to accepting the risks of being a snitch, one of which being stitches.

So, to answer your question, it reall depends on a lot. Circumstances, methods, ultimately, risks. Should they? Well, they are potentially ruining another's life in order to help themselves, regardless of anything else, that at least deserves the RISK of getting stitches.