"Microsoft SQL Server on Ubuntu delivers an optimised, cost-effective database platform"
Of course not, it's not free so it's not cost effective compared to the best database, which is PostgreSQL.
Integration with Active Directory group policy seems also a really bad idea since it allows insecure proprietary software to control your Linux machines.
This is a smart move by Canonical to court enterprise customers, especially with the Red Hat change of ownership chaos and churn.
Also proprietary software is not insecure just be being proprietary.
And if that's the extent of your understanding of what the software does, then you aren't really qualified to give an opinion on its security.
And plenty of business apps straight up require Microsoft SQL Server. You should be thrilled those now no longer need a Windows license, just the SQL Server license.
I still miss some of the tool ecosystem (like schema/data diffing tools from RedGate) from my SQL Server days.
Active Directory has its own share of problems, but the benefit of having a central location for policies which enforce them on the connected machines is a security plus despite the addition of attack surface by itself.
While I first thought that AD integration regards group policy looks like a hard architecture mismatch, it is interestingly not. Take the Windows Registry with millions of keys vs. the thousands of etc files and their thousand sub settings.