Ok, they are a marketing/AD firm, it would have been stupid for them not to do this EXACTLY the way they have.
Think about it for a moment, if they went to Apple well in advance, Apple could very well have used a different name, which I will get to why that would be a disaster for this company in a moment.
Now, they are coming in at the last moment to make the request and what happens, now every time someone who needs a marketing/ad firm looks at their iPhone 6S, they will think of this company and how they managed to use Apple to get TONS of free publicity and if they can do something like that for themselves, what can they do for that person or company that needs their services? It's really an absolutely brilliant marketing move and one that won't work if Apple did use a different name.
If they did nothing, then those that need the services would wonder why they didn't even try to make a marketing move here.
So, really, this company had no choice but to do what they did or they wouldn't be a decent ad/marketing company.