> When a person registers a domain name, they become the owners of that domain name.

They may own the name such that it would be improper to allow someone else to register it, but there entitlement to service from the registrar is based on the terms of the contract they have signed.

> ICANN should probably get involved and punish Network Solutions for this action.

What specific ICANN policy has been violated?

> Network Solutions might be within their rights to choose to no longer 'host' the domain name themselves, but in that case they must be obligated to arrange for a transfer to a different registrar.

They are obligated to process a transfer at the request of the owner and new registrar, subject to certain timing and other rules. They are not, AFAICT, required to arrange such a transfer proactively.