I may have misunderstood the logic in the updated .sbi, or at least the way the \uninstall\ keys in the registry work. The script in this case is looking for
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Curr entVersion\Uninstall\{E30D8B21-D82D-3211-82CC-0F0A5D1495E8} (or the WOW6432nODE equivalent), whose presence is correctly causing it to skip over the reinstall. (The "Get Related Product" function on {B59F5BF1-67C8-3802-8E59-2CE551A39FC5} returns the same key.) But when I try to test this by uninstalling the C++ 2013 Redistributable (x86) package, although the package is removed from the list of installed programs as seen in the Control Panel, that key remains in the registry, and thus the sbi script from that point forward acts as if it is still installed (i.e. skips the reinstall) even though it isn't installed.

Furthermore, if I rename that key, the sbi script will then install the package each time I run it (which was the original complaint.) The package shows up in the Control Panel list of programs, and otherwise acts as it it's installed, but the key in question is not recreated in the registry, thus causing sbi script to redundantly reinstall it each time.

It's possible that I've muddied the situation trying to test it under different scenarios by manually installing and uninstalling it multiple times. And it may be that part of the problem is that the Windows uninstaller is failing to remove the \uninstall\ key, and/or that there is some kind of mismatch between the key that the redist installer is using and the one the sbi is checking. Certainly Microsoft deserves our awe for making it complex almost beyond the limits of mortal comprehension

But I guess what you're saying is that theoretically the sbi logic should handle this, particularly with the newer redistributables. But it wouldn't hurt for me to add my own test to avoid the redundant reinstall problem for this particular C++ redistributable. (The fact that the key may change is a problem for maintaining the application install script, but it wouldn't change unless I used the Redistributable Manager to download a new version of the redistributable package.)