Looking up stuff on the internet is not   

No airport operator or owner can refuse a landing, especially when it involves and emergency [Patient care in this discussion].

A hospital helipad is an airport under definition.  Additionally, even though privately owned, it may be considered a "Limited Public Use."  Meaning the use of the helipad is open under certain business functions to those who maintain a function of that business.  A medical patient being transported from a "Referring Facility" to a "Receiving Facility" most certainly falls within that business function.

If a medical patient is denied care due to not having a non-employee pilot federal credentialing on file, whoa be it to the hospital.

Now if a pilot is on contract to a particular hospital, i.e. vendor contract, then the hospital can require those credentials on file.  But to deny a landing with a patient?  Not a chance.