The armed groups in Sudan need outside help. The two powerful neighbours who can exert immediate pressure are Sudan and Uganda. Having those as a guarantor, and not undermining, is bound to help.
Are all of the actors in the neighbourhood good actors? No. You're dealing with who's actually in control and who can exert pressure. Behind this accord, there's the U.S. and there's the U.K. and a whole bunch of global powers who think this is a way to ensure a level of security in the country. It's not a place where you can choose your partners. You have to choose who's there.