I don't see any problem. There is certainly a drop in penguin numbers, but no evidence that it's due to human visitors.

Boulders Beach is a great place to visit. And you don't even need to go pay to see the penguins. If you walk south of the pay-area, you will often see penguins along the shore, living just fine without all the "conservation measures" found in the pay-area, such as plastic nesting places and tourist management.