It is demed a best practice to ensure that SQL Server is running on a non default port.
This condition will return a result if the instance being checked is running on either the default (1433) or a dynamic port.
There is a V2 of this AC which does not require the use of xp_regread, but is not able to return the dynamic port being used.
If port information is important use V1 if not use V2.
Further Reading:
Configure a Server to Listen on a Specific TCP Port
Configure the Windows Firewall to Allow SQL Server Access