Nice script

The following is missing AND is_read_only = 0 in select

INSERT INTO @LoopExecuteScripts

SELECT 'ALTER AUTHORIZATION ON DATABASE::' + name + ' TO sa'

FROM sys.databases

WHERE owner_sid <> 0x01

AND state_desc = 'ONLINE' --AND is_read_only = 0

and it will work without errors

Regards

IgorMi