If you can't impress 'em with brilliance, baffle 'em with bulls**!
That's the credo that salesman lives by. His quote "He says that as long as I don't intend to play at crazy levels, it won't be a problem." is correct, but it has nothing to do with his self imposed ratio.
Any amp can damage any speakers if one is stupid.
You can have a high powered amp with low power rated speakers or a low powered amp with high power rated speakers.
All you have to do is listen and use your head.
If it starts to sound bad, distorted, funky, or in any way abnormal, turn it down immediately. That's the sound that something is not happy.