Tom,
You are correct. A silent install of ArcGIS Pro Single Use automatically turn on LOCK_AUTH_SETTING which means Pro will look to the licensing setting in HKLM and copy it to the HKCU registry hive and open with that setting. However, it prevents you from switching to other licensing type and even authorization/deauthorization. The assumption is that the administrator should complete the software authorization along with the silent install.
In your case, you just want the install and then authorize it separately. Is this because you don't have the licenses yet or you don't have the provisioning file? If the latter, you can create your own provisioning file which is just a text file. Just copy the following into a text editor and save it as .prvc file. You will need to supply your information and the authorization number for the Basic license of course.
// User Information
First Name=ESRI
Last Name=Employee
Organization=ESRI
Department=Dev
Email=abcde@esri.com
Address 1=380 New York St.
City=Redlands
State/Province=CA
Location=United States
Location Code=US
Zip/Postal Code=92373
Phone Number=909-793-2853
Your Organization=Commercial/Private Business
Your Industry=Other
Yourself=Other
// Features and authorization numbers
Desktop Basic=ESU123456789
If this is not an option for you, then yes you can run the Software Authorization wizard from the ArcGIS Pro installation directory. However, you will still need to provide all the information above manually.