We don't know that Maya and company created exos themselves. It was during that time but we don't know if that was part of Maya's project or not. And no, they didn't make themselves exos. What you are remembering is Vex 4, where the 4 scientist are using remote controlled mechanical frames while their bodies and minds are safely back at the academy behind a warmind firewall (think like the movie avatar) That is considered by many to be the exo precursor technology, but not exos Both Maya and Chioma are involved in that. And Chioma isn't dead. After Venus, Chioma and Maya went to work on other projects and have been apart a long time.