[@TheWindel]
The way I see it, if I answer yes then BS will attempt to leave the Nexus but be wiped into nonexistence as a result, and if I answer no, I have to fight Helena. It seems like an illusion to me.

It may very well be what the offer is, but then again, it's handed to us on a silver platter. Why would someone do this, especially to someone she called "bone head" a few seconds before.