If you are not bringing business with you, look like someone who may not immediately draw in clients, the manager may stick with the company rules. But don't be fooled in thinking the treatment you received when you got your job is the same for everyone. Those rules are very flexible, just like car prices. Some people get stiffed when buying a car and others get a great deal.
It's always an individual circumstance and many hiring situations are individual and will remain private between the person getting the deal and the employer. So, if you are the shit, then it doesn't matter what cert you have. The manager is not going to turn you away if you are presenting true value. On the other hand, if you are just some eager, enthusiastic trainer off the street with your hand out, well there are hundreds like you and the manager has been down that road before and has no reason to bend the rules for you because you'll be gone in 7 months anyway. In that case, you better possess one of their "preferred" certifications.