The former presidential candidate said the group has the right to express themselves.
While speaking at the Holy Cross Cathedral in Lagos, the economist said the separatist group were nothing more than a public nuisance, and had the right to express themselves.
He said, "People have the right to say they've been unjustly treated. To take away that right from them is to say you want to enslave them.
"When you talk about modern slavery, it's the most grievous violation of human rights in the 21st century.
"I've not seen what terror they (IPOB) have committed. They are not, I repeat, quote me anywhere, any day, they are not a terrorist organisation.
"That's just a political thing. It doesn't make sense which way you look at it. It's just a political thing. You can carve any name, you can be IPOB or ITOT, it's just a name.
"Nigeria is going through a necessary and interesting phase of its evolution as a country. I am not one of those unduly worried about the things going on in the country.
"They are part of the thesis and anti-thesis that will produce synthesis that is a nation."
On Wednesday, September 20, the Federal High Court in Abuja granted the Federal Government an interim injunction proscribing activities of IPOB.
The group's combative leader, Nnamdi Kanu, not been seen in public since September 14 when IPOB alleged that the Nigerian Army took him into custody, an allegation that has been strongly denied by the military and the presidency.