A difficult question to answer to. First of all, please find below a communication from HRW calling to not defend Rwanda.

HRW criticises Rwanda's UN council seat
Human Rights Watch criticised Rwanda's virtual guarantee of a seat on the UN Security Council next year, saying on Monday it shouldn't be on the UN's most powerful body when it is protecting a Congolese ex-warlord indicted by the International Criminal Court.
Implicated in crimes against children

HRW's UN director, Philippe Bolopion, said on Monday if Rwanda wants to be a responsible Security Council member it should cut off all support for Ntaganda, actively seek to arrest him, and surrender him to the ICC.

"By allowing its territory to be used to protect and arm an ICC-indicted war criminal, Rwanda is making a mockery of the decisions of the same Security Council it is slated to join next year," Bolopion told AP.

"Bosco Ntaganda is not only implicated in horrendous crimes against civilians including children, he is also undermining everything the Security Council has tried to achieve at great expense in the region for the last decade."
http://www.news24.com/Africa/News/HR...-seat-20120619

I think that HRW resumes very well the situation: Rwanda will be a UNSC non permanent member next year. For many permanent members (at least 2), this means more leverage in the extended UNSC.
This tends to go in the direction given by David on why are there some difficulties in publishing the proof of Rwanda support to M23.

On the other end, DRC gov has been conducting a strong diplomatic offensive in Uganda, Tanzania, Burundi and Angola.
An offensive to which Angola responded positively, ensuring DRC of its support and SADC sympathy. This means that South Africa, Zimbabwe and Angola are, until they do something different, on DRC side. (Many articles in French can be found. I just add a link to one: http://www.mediacongo.net/show.asp?doc=20667)

The situation is quite tense in the sub region because we could end in a regional war in Africa, Central Africa against Southern Africa, on Congo soil.
Therefore lights need to be brought on allegations of Rwanda support to M23 (Rwandese have been made prisonners or surrendered).
Hopefully, discussions started as Rwanda foreign affairs minister is in Kinshasa.

And to finish and to illustrate why war criminal in DRC have to be turned to ICC, please find a link to Prosecutor address at Lubanga trial.
Just to remind who people like Bosco Ntaganda are (Bosco Ntaganda was under Lubanga orders in Ituri and he is wanted for similar crimes).

Prosecutor’s Address At Lubanga Sentencing
2. Thomas Lubanga’s recruitment included particularly cruel treatment. Children were abducted, their families forced to accept the situation, instead of obeying their mothers, children had to obey commanders. Children were trained by terror. They were trained to kill and to rape. The children were launched into battle zones where they were instructed to kill everyone regardless of whether they were men, women, or children, all were the enemy. The harm produced by this cruel treatment continue even after demobilization. Those who didn’t die as soldiers, they have permanent physical effects or they have on-going psychological trauma, all them still suffer.
In addition to these two aggravating factors, the Prosecution will like to highlight two aspects that should not be invisible. The crime of recruiting children as soldiers included as a fundamental aspect a gender discrimination, and fourth, the crime of recruiting children as soldiers denied these children and their generation of their right to education. I will briefly elaborate on both aspects:
3. Embedded in the recruitment of girl soldiers was their special use as sex slaves. In the training camps, girl soldiers were the daily victims of rape by the commanders and soldiers. The Prosecution chose not to charge this gender aspect as a separate crime because gender abuse is an essential part of the crime of recruiting girls as soldiers. All the girls recruited would be raped and abused because they are girls.
As emphasized by Ms. Radhika Coomaraswamy [the Special Representative of the UN Secretary-General for Children and Armed Conflict] in her amicus brief to this court, girl soldiers are too often invisible. “Wife” is the word used to make this crime invisible. A severe sentence would ensure that the gender suffering of these girls and other girls will no longer continue to be invisible.
http://www.lubangatrial.org/2012/06/...ga-sentencing/