Yes, I would pot it up quickly in a tiny seedling tube. Keep it lightly moist but not soaked.
The tiny ones on the mother plant I would remove them with a chunk of cane each. Do the same with these as you did with the other keiki. I have managed to grow plants on like this.
I would unpot the mother plant and try to save the new shoot, if you leave it with the dying plant it could well die too.
i added it to a pot with my generic pink Phalaenopsis that has moss that stays moist for two weeks at a time. I put it under about 1/10 inch of moss where it can get air but not dry, is that ok?
That should be ok Tosh, I often put keiki into the side of other plants when I'm walking around my orchids outside. If it's not going to survive you will see it start turning brown.
Tosh, I was following your post. How did that little keiki go, did it survive? I too had little keikis that I wrapped in spagnum moss and put into a tiny pot, 2 inches and suspended it from the roof of the greenhouse, and lo and behold in 2 weeks, roots everywhere. Then I potted it in light bark and pearlite, and is as healthy as ever. Good luck.