Stopping own iPhone from being erased after being deleted from within Find My iPhone on iCloud.com
I am not sure if the same would happen in all similar cases but I just want to tell what happened to my friend's iPhone after posting the above.

For about two weeks she made sure her phone did not connect to the Internet by disabling the Wifi and taking out the SIM card. In the meantime, she wrote down the details of her important contacts missing from the iCloud. Once she wrote down everything she needed, she turned the Wifi on and ... nothing happened. The iPhone connected to the Internet and continued to operate as usual as if the Erase iPhone option was not activated via iCloud.com.

When we checked the iPhone's status on iCloud via Find My iPhone, it only appeared to be offline. Out of an abundance of caution, we disabled the Find My iPhone menu option through the iPhone's settings. This caused the iPhone to be removed from the list of Apple devices listed under the Find My iPhone menu on the iCloud associated with her Apple ID. She has been using her iPhone as usual since then.