That still implies there was a target in mind. But also they would've had to assume the access would be relatively short-lived. This means to me they had something specific they wanted to get access to, didn't plan to be there long, and weren't terribly concerned about leaving a trail of their methods.
Why couldn't they have had 50 or 100 targets in mind, and hoped that the exploit would last for at least the month (or whatever) they needed to accomplish their multiple, unrelated goals?
I think your imagination is telling you a story that is prematurely limiting the range of real possibilities.
They don’t want tons. They want the few important ones.
Turns out it was easiest to get to the important ones by pwning tons of random ones.