Sorry about the syntax, but every way I tried to word it in my head sounded too whiny for a thread title, and here we are. So, this is a simple enough thing I've noticed that honestly seems like an accidental oversight to my eyes all things considered.
So, if you're ADS'd and inevitably you burn through your ammo and you go to quickly swap to your secondary, this works as expected if you're using the "Select Primary" or "Select Secondary" or "Select Next Weapon" or "Select Previous Weapon" key bindings to do it, but if you're using the "Switch Primary/Secondary" key binding, you're in for a bad time, because it is the only key bind relating to swapping to those weapons that will not 'un-ADS' you to force through the weapon swap. It will instead politely ignore that key press while you flair around in confusion before getting shot by the guy who rushed you.
Now, I could see an argument for you not wanting it to pull you out of the ADS, but honestly, in trying to think about a situation where you would actively seek out this setting as a player, I see the main appeal of this setting being its button efficiency. It takes two independent binds, and allows you to easily toggle between them with a single key, great! Except, that's not actually what it does, it operates slightly differently (ie. not pulling you out of ADS), and so it's actual purpose is confusing. Either that or this is just an unfixed bug on the back burner while much bigger fish are being fried, which is totally understandable, it's not game breaking. That being said, after realizing the differences in how the ADS+binds work, I felt compelled to post about it, because personally I love the "toggle primary/secondary" bind as a setting.
After first using it in R6, I've found myself wanting it in virtually every other FPS I play, and was really excited when I saw it among the binds of Sandstorm, I just hope it can be fixed to really shine as a feature!