As the article points out, most of that is companies trying it on with no real intention of following through. the current total data centre capacity in the UK is ~2GW with another 0.8GW under construction. There's no realistic prospect of 9GW of them being built in Scotland.
Also the argument that "too much of them would be bad" applies to almost everything, and isn't a reason to allow none of them, regulation exists and should be used!