The "occupation" bit isn't the only thing Hari got wrong. He completely leaves out French involvment in the mess in the DRC. According to Roméo Dallaire, the Canadian UN force commander in Rwanda during the genocide, the French were very involved in the Rwandan genocide and in the DRC war:

The Hutu army went ‘mad with joy at the prospect of imminent rescue by the French. Their renewed hope and confidence had the side-effect of reviving their hunt for genocide survivors’ (the RPF offensive had diverted them). ‘The génocidaires believed . . . that they now had carte blanche to finish their gruesome work.’..

…Turquoise’ deployed too late to hold up the RPF advance - one of its main objectives - but it did create a safe zone for the retreating Hutu army and the Interahamwe militias to carry out more killings, as they prepared to cross into Zaire with many of their weapons and with their structures intact. The chaos that followed has not let up: it’s known as the Democratic Republic of Congo.

According to most of the commenters on Harry's Place, blaming the whole mess on 'coltan' is completely silly.

Hari on coltan. I do wish people would get this right. It’s actually colombo-tantalite (If there’s more niobium, what the colonial cousins call colombium, in the ore then it’s colombite, if more tantalum in it then tantalite, but all such ores contain both metals) and very little of it comes from the DRC. There are only a few factories in the world capable of refining the stuff (ULBA in Kazakhstan, couple of places in the States, one in Germany I think) and they have all agreed not to purchase ore from the DRC.

Hari's portrayal of the Rwandans is pretty unkind, and, according to the commenters at Harry's and every other account, not very accurate.

It's not clear why Hari's account is so off-base, but from what I can see, it seems like he was given a guided tour by the UN:

On the long journey in an armoured UN vehicle, the questions seem so obvious, so trite. How could a government led by genocide victims suddenly commit their own epic crime against humanity, for nothing more than money?

The UN has a history of favoring the French and opposing the US (and Britain). They're probably not very happy with the Rwandan Tutsis after they exposed UN incompetence during the genocide. Don't those Tutsis realize how much they cost the UN in public relations capital, being slaughtered by the hundreds of thousands that way? How could they be so rude?