This should be such an infrequent occurrence that the cost should be negligible. Surely their $10/month plan has enough margin that this can be covered?

There is likely a cost to the infrastructure necessary to enable calling 911 that scales with the number of users not the number of 911 calls. So likely the margin doesn't cover it.

Every cellphone without a valid service plan is still required to be able to call 911 in most places of the world, including the US, and carriers eat the costs. It should be obvious why.

Frankly it's weird they're making a clone of a classic touch tone corded phone and somehow get around this. Especially for a kids product when we teach kids to call 911 in an emergency.

Donate my time and services? Sure.

Donate the cash? To a business? … So, you mean, paying someone else's profit margin, while they hold lives hostage? Immanuel Kant says you don't negotiate with terrorists.