Hi I desperately need help here

First time home owner

Today a roofer who came to do other work decided to be smarty pants and seal my chimney without getting my explicit consent ---By the time I knew abt it, he has done it

A few hours later, I sensed something is not right and decided to research on the solution he used. Instead of using the appropriate waterproofing solution, he used this
http://www.quikrete.com/productlines/concretesealer.asp

It is a concrete sealer and I am suspecting this is detrimental to the chimney now because it doesn't allow the chimney to breathe. All my readings point towards the fact that the chimney sealant should be a water repellant material suitable for brick use, and brick and concrete are two different things

Can someone please offer insights on how severe this problem is , and how should I solve it ? I intend to haul back the guy and point blank tell him this is a mistake, at the same time I want him to undo his actions in the correct manner

Appreciate your help , thanks !