So using Linux, Windows, BSD or MacOS servers are malpractice? I think you might have over stated your case. So are you waiting for a memory safe Herd re-write? A memory safe any OS will be decades away if someone wanted to start tackling it now.
Latest examples, Windows 10 secure kernel and Device Driver protection.
https://myignite.microsoft.com/sessions/36925
Or the new Windows USB stack, written in the P language.
UNIXes, not so much beyond patching C exploits.
Windows 7 was released in 2009. There are substantial proactive improvements that Microsoft cannot feasibly backport to older OS versions even if they're still within the support period, and the corporate culture was simply different when Windows 7 was released.
If that system exists, it sounds disgusting and unethical. Paying for something changes the nature of the transaction.
If you sell it as "secure", yes absolutely. And there are many applications where you would not be even considered as a contractor for doing so. There is increasing number of situations where you want to provide hard guarantees (written in contract) about quality of the software and service you are providing. "we are using Linux" sometimes is not good enough.