I think Desert Perpetual explains why her Vex are sticking around. They want to learn how to use dark matter and quantum entanglement to manipulate timelines, and Kepler is a hot spot for dark matter because of III's death. There was also the matter of the singularity that threatened to engulf the system. Levaszk wanted to feed the singularity so it consumes Kepler and Sol; the Vex set up a quarantine to keep the area around the singularity and III's corpse sealed off. Maya herself is done her business on Kepler, but her Choral Vex are not.

She's not there for us. She's trying to find Chioma... who she never killed... Spoilers. [spoiler]Osiris was killing the copies. She took off because she was afraid, he might get to the real one.[/spoiler] If you did that side mission in Lightfall... (Veil Containment) that references the ICoV logs of Chioma. Here: [url=https://www.youtube.com/watch?v=e-Xf8uL2oco]Veil Containment | Eleventh Research Log: "Maya's Dead" | Lightfall[/url] And here: [url=https://www.youtube.com/watch?v=_zXKHu7HXOY]Veil Containment | Thirteenth Research Log: "A... Vex Signature? What's... MSund12?" | Lightfall[/url] Credit: Destiny Lore Vault [i][b]"My hands can be bloodied. Let the children have innocence. And in my dissolution, I will find peace".[/b][/i] [b]- Chioma Esi[/b] Here: [url=https://www.youtube.com/watch?v=C-_ysHJAo0E]Veil Containment | Fourteenth Research Log: "The Vex Simulated Copies of Us" | Lightfall[/url] The plan was that Maya was going to sacrifice herself and give the Echo to Chioma. Maya made Chioma suffer through the simulation over and over, so that she would not act emotionally when the time came. However, we intervened. Ignorantly... and manipulated. Did you ever wonder why every time we found a dead Chioma copy, Osiris was there before us? Including the final confrontation in Echoes, when we found what we first thought was the original? Yet, when the battle happened? Osiris wasn't there. He met us as we entered... but was absent when the Conductor escaped. I think it was to avoid get exposed or Maya getting into his head, like she did to Saint. What's Osiris been doing btw? Time anomalies are kinda his thing.

I mean I think the Vex keeping III’s body quarantined while they continue their dark matter research makes perfect sense- Her business for coming to Kepler was concluded, she failed, doesn’t mean there wasn’t anything left to gain. Also makes a lot more sense if she knew we were there at the summons of III.

Ever heard of the spoiler tag ? I don't want to know what happens when I play it for free from PS Plus