Google has a policy that they delete permanently the contents of any account that has been suspended for 30 days or more. They do this to comply with European GDPR regulations (which require they not hold any data they no longer have the users permission to store, nor have ongoing legitimate interest in), and they have written it into their own privacy policies.

Therefore, this account and all the data contained is already gone. The most they could do is allow him to create a new account with the same name, but to my knowledge that isn't supported technically in their systems (too many bugs to be found by re-using unique identifiers).

Changing this would probably be a huuuuge undertaking, since every Google product would have to be modified to expect email addresses might be reused for a new account. And some products are in maintenance/bugfix only mode, so those products would probably have to be sunsetted if the changes were too invasive.

That's why they stand by their decision - they don't currently have the capability to implement any other option.