Somalia needs the IC, it can't be sovereign if it cannot control a majority of territory it claims as theirs
Last time N&N had an issue with UN diplomat in Somalia they expelled him and the UN was forced to replace him with another.
If the UN tries to interfere in Somalia's internal affairs N&N can just expel them again, and they will again replace those representatives.
You have to understand Somalia is weak now so N&N cannot take such decisions lightly, but Deni's obstruction to the election and UN support of that even in the slightest form can lead to them losing favour with N&N.
So who is propping up N&N, if not Beesha Calamka ? the answer is bilateral relations with powerful nations, N&N flirts with established blocks in the west and east, as well as potential Eri-Ethio-Somalia block.
N&N also have legitimate support from the overwhelming majority of Somalis, and build institutions, every year the annual tax income increases under N&N. Army is getting more powerful day by day.
Right now what most people is asking themselves is why Farmaajo is playing with his food and not dealing with Deni, the answer is simple, he wants to resolve things politically not strong arming, this is why Farmaajo support is catching on like wild fire all across Somalia particularly PL.
The Somali people are used to leaders who strong arm their way through opposition, remember PL speaker attacked by Deni killing his staff in broad daylight, thats what Somalis expected from Farmaajo to do to Deni.