As a first approximation: yes. Nobody can pull it down because not even the tallest human is tall enough to reach it. By far. So that is the answer to that.
On the other hand I assume you mean: Is it possible to pull it down with some machine? And the answer is yes, it is possible to pull it down with some machine.
Entirely within the demonstrated abilities of humankind.
If we want to, have enough money and time, we could make a machine which captures it, takes it to Mars, lands it there softly, dances the cha-cha-cha with it there, launches again back to Earth and lands it softly here. Entirely possible. Only a matter of time and money.
It is not a question of impossibility. It is a question of how much time you have (remember it is drifting out of your airspace) and how much money you want to spend on it, and how certain you want to do it, and how safe you want to keep your personal and people on the ground while doing it.
The balloon was very high in the upper atmosphere, above normal commercial airline flight and above the reach of helicopters.
If balloon pulling is a regular occurrence you can set up infrastructure for it. Devise some different approaches and test them to see what works.
If they waited that long, the balloon would have drifted out of US territory and the politics of downing an object over international waters would have been very sketchy. So yes, it's probably possible to engineer a solution to down a balloon using some non-destructive method, but there simply wasn't time to test it out and figure out what works.
