I think if the other kids in your group have a positive working dynamic then terming this infant may be for the best. I've hung on to kids and worked really hard to help them only to either end up with the child not settling in and the rest of the group being negatively effected, or the individual does eventually settle in but at the expense of another child due to the neglect they have endured due to an individual needing one on one care.

A new child may be a screamer and not sleep, but that usually doesn't last once transition, and I wouldn't let any future possibilities that you can't possibly foresee determine how you handle this situation. Not to mention, this child sounds like they not only pose a risk to themselves, but to the other children in addition to high chances of damaging some of your property.

Just as a side note, in my contract I give examples of reasons for termination but I do not limit it to anything. I make it clear verbally and in writing that parents and provider can terminate care at any time for absolutely any reason as long as the appropriate notice period is given. The only exception is immediate termination without notice and loss of initial deposit, and that is in very specific instances.