I'm probably that annoying guy at the range in Saskatchewan, dosing SKS's with windex.
It's not a chemical thing. Straight hot water works awesome, soapy water works awesome, Hot soapy water is even better. I don't claim that ammonia (of which there is pathetically little in Windex) is any better or worse at removing corrosive salts than anything else.
It's purely a logistical thing.
It's portable, doesn't leave nasty residue, like antifreeze, or a gallon of your favourite gun oil. It comes in a convenient spray bottle, costs about a buck at the dollar store, and resists freezing better than water. And it works. Helps dissolve carbon too. Also works nicely if you find a smear of cosmo after heating the rifle up. Smells nice to boot. And if you spill it in the truck, Oh well, it evaporates, and smells like clean truck for a while.
Plus! While I'm waiting for the wife, I can clean the windshield on my truck, clean the steering wheel after driving home after a particularly oily day at work. Clean the coffee stains out of the cupholder in the centre console etc. All for a buck and some shop towels, that I carry anyways.
Sure, I could bring a portable generator to the range, or rig a 1500 watt invertor to the truck, and a kettle, or a esbit stove, thermos, whatever. But a bottle of Windex-like substance does it good enough to buy me time until the next proper cleaning, and I don't have to tow a trailer full of "range-gear."
Wanna shoot in the snow? Alright, here's level 2. Refill that handy windex-like spray bottle with el-cheapo-crappo $3 a gallon Blue windshield washer fluid. It doesn't freeze, down to -35, does all the things Windex does, packaged conveniently, etc. Got the rear window of the truck to gross to back up to a trailer? No problem! You just happen to have a spray bottle of washer fluid and some shop towels!

Happy meals for everybody!
So yeah, to sum up, Nope, chemically Windex isn't really all that exciting. But Logistically, it's better than most. And Ballistol is a crappy glass cleaner.
