Like Charles I also agree with your QA manager.
Already in your product development process, you should have knowledge about the ingredients/raw materials you are going to use. This information is in the specifications. You should also know if the supplier can meet your requirements. And of course you need to know if there are reliable suppliers for this raw material/ingredient.
Okay, say, you do it your way and use whatever you like in testing phase. The product is good and customers really want this product after the (kitchen) samples you send them. Than you are going to introduce the product in production. As I understood, you have the impression that you should request all information at that moment (and you know the way it is, customer like the product and really want it supplied next week).
1) What if the supplier does not send you the information on time? QA can not perform risk assessment, HACCP study, make finished product specification, make labels, performs test to check the sample to your requirements, approve the supplier. Sourcing can perhaps not find the product in the quality you want for the price that you want in the quantity that you need on time. At least sourcing does not have ability to negotiate about price and conditions.
2) what if the product can not be accepted due to not matching your requirements (microbiology, allergens, etc.) You have to find a comparable product and do all your tests again.
3) what if the supplier does not fit your organization?
Well, If that customer is really demanding, I know what will happen and you know too, and you know it is not really food safety management system.
You really should know the hazard or conclude there are no additional hazards from new raw materials/ingredients before you introduce it.
I will end with 3 real cases, that I have observed in the time being an food safety auditor.
A) company of ready to eat meals. Product developer buys his ingredients at al local Asian toko. The labels are not in the language of the company. After the product was developed, tested and approved. The product could not be sourced on industrial level. Resulting in using small glass (!!) jars of 200 gram in production. Also resulting in some creativity of the QA department, when the label has to be made. She uses an ingredient declaration of a similar product, because the label could not be read. For the risk of glass they found a solution: in preparation room some one was taking the products from the jars and every jar was than washed and checked for damages. But for the costs this extra handling brought, they did not found a solution. Finally during the audit, it was observed that the label and finished product was incorrect and that they even were using a product that was legally not allowed in the products they were making.
B) also a company for ready to eat meals. the product was based on local grandmother's recipe. Product developer uses products from supermarket (Aldi). After the product was developed, they could not find a suitable product on industrial level. The product from the Aldi was somehow specific. The supplier from the Aldi could not be traced. Also this company is buying this ingredient (some kind of local ginger bread) at the Aldi store. in stead of specification they use the detailed ingredient declaration on the label.
During audit, however, they got a non-conformity, due to the fact that Aldi supermarket did not meet the requirements they had for their suppliers.
C) bakery company. Product developer was very creative and had a big garden with an Elder. Because elder berries are claimed to be healthy, she makes muffins with the Elder berries from her garden. The product was very much appreciate by the internal team and for the sample to the customer, she needs more berries. She starts to pick them in the nearby forest. After that for new samples she was asking around if some one knew were she could find Elder. It was found that elder berries are hardly to get on industrial level and she was really going to pick he berries next to the highway. Fortunately the QA manager stopped this project.
So, just some over the top examples. Just take care what you bring in your company and make sure you know what you want to know about it. Maybe just, can I get it in big amounts? will I get it for the price I want? and Will the lady, that I pay to control food safety and quality, agree with it? Otherwise it is just a waste of money, time and energy.