Well, you don't know that for sure. And you can still respond in a calmer way and explain why you do not want to do that and how you would rather do it in a way where the customer and you can actually develop a better relationship, especially considering this client is new in that he is fresh in just taking over this company your company has worked on.

Because the company is now under new ownership, it's best to talk to this client with "congratulations" and what are YOUR plans and goals that I can help you with in respect to where YOU want to take this company you have taken over.