Why do you think shuttles can "tow" satellites but not warheads? Shuttles can stay in orbit for weeks so they are reserved for when tensions are high. Launching anything from the surface will be almost immediately detected, giving opponents far more time to respond than something that immediately begins re-entry the moment it is deployed from orbit.
If you're going full fantasy thinking (since launching weapons from space would violate every weapons treaty both the US and USSR signed) the shuttle would have been an enormous and obvious target as it orbited Earth. The shuttle could have easily been knocked out by an ICBM and sub orbital weapon detonation--it had no real way to avoid it even if it knew weapons were being launched at it.
If you're arguing there's some need for faster response than a nuclear sub launch, launching nuclear cruise missiles from B2 bombers makes far more sense than lugging warheads up to low orbit. We have more B2s than we ever had shuttles.
But it just does not make sense vs. submarines as a launch platform. Three or four shuttles worth of weapons is nothing compared to a single Ohio class nuclear sub (20 missiles alone, and there are 18 of those subs in the US Navy).
You are not getting it. You simply are not getting it. That's okay though, conventional thinking is overly predominant after all and it's okay that you can't escape from it.
Also, treaties mean jack shit. Both countries pledged ultimate elimination of nuclear armament in NPT and look at where we are now? Do you think any treaty will matter if a hot nuclear war breaks out between two nuclear powers? Pure naïveté is what you have.
This is ridiculous logic. Sure, the Shuttle was technically capable of carrying a nuclear weapon since well, it could carry payloads. But it wasn't specifically designed for that purpose, just as how the Falcon 9 isn't designed specifically to carry loitering nuclear weapons either, but is perfectly capable of doing so.
If the US wanted to station nukes in orbit, they wouldn't do something as dumb as putting them up using a crew. They'd do what any sane person would do and put them on an uncrewed nuclear rated vehicle (ie the Delta/Atlas rockets). It would be way cheaper, and most importantly, would get around the concern of risking the crew.
If the concern was only launching them when tensions are high, the US has a 'rapid launch availability' program for launch providers to be paid to be always available for emergency launches. The Shuttle was essentially incapable of a similar rapid availability due to how delicate it was.
On top of all that, what exactly do you think a ~30 minute early nuke launch (compared against ICBMs) would accomplish against the only two targets the US has been in any position of potentially going to nuclear war against? The number of nukes (optimistically ~14) that a Shuttle could carry can't take out Russia or China's retaliation framework on its own.
