What does this even mean? Especially the first bit

3 throws per second is the rate of action required to perform juggling literally. The implication is that communicating between the miss that causes the fall and the event of dropping the ball must happen in less than 1 second. Translating back to the metaphor, communicating that the ball is being dropped before it hits the ground is a task as hard as the juggling itself.

It means they're for some reason talking about juggling balls.

Yeah but only in earth gravity. Depending on your remote work location things change substantially, though I’m not sure exactly how in your mixed metaphor.

Remote work is like juggling scarves -- especially if there are more than a few time zones in between. Things can stay in the air a bit longer which also can mean juggling more.. and moving your hands twice as fast.

And then also having the time to put those scarves in the laundry.