It makes sense.
It's Newton's third law in operation. For every action there is an equal an opposite reaction. The maximum reaction force of the bridge is it's load rating.
You need to consider that the juggler is also applying a force to each pin to overcome the effects of gravity in the act of juggling.
The total reaction force of the bridge is therefore the weight of the juggler plus the weight of the pins,
plus mass X acceleration of each pin during juggling.
This will exceed 57 kg and the bridge will come tumbling down.
Regards
Steven