While Kaine is not a Mutant, that doesn't mean he can't be a part of the X-Verse, Kaine would make a great addition to the X-Family. This would allow that audience to see a development with Kaine in ways that would not be possible at the Spider-Office. Longshot is not a Mutant. Yet, he's stuck in the X-Verse. Making Kaine an X-Men makes a lot of sense storywise. What is a big tragedy is not loaning Robin Vega to the X-Office, and she's a Mutant. The character is stuck in limbo. If Kaine goes over to the X-Office, he would not be stuck in limbo now the focus is on Silk, Spider-Gwen, and Miles Morales...