What’s your rationale for keeping it?

Because it won't be worth the time it takes to send my Bitcoin back and fourth to separate funds cleanly. I mean I don't think the fork coin will be worth anything anyways. Might as well keep it. Unless it has a price of like 10k per coin minimum. And if it does get that price through some crazy circumstance, I would consider selling half of it then and keeping half as a little keepsake reminder for myself.