You consider that little thing 'nagging'? Blimey. The way it was talked about, it was made to sound like something that was large and in your face, interrupting viewing something for free.... (with the verifying, maybe you haven't told it to trust that device).
They are offering the episodes free, with a 3 day window to view at your convenience, as many times you like, at the period of when it would have previously been aired, with a minuscule thing to say you can subscribe for access to everything. Normally it would be aired once on 1 day, with advert breaks repeatedly.
Yes, Apple would like to gain more subscribers, and the fact the licensed for the production company to make new Peanuts content, that is likely to be exclusive, which is something that was not happening before this. Also, it the rights could have been bought by Netflix or Amazon Prime, and there's NO CHANCE they would have given the free option.
Again, you and others seem to be blaming Apple for something instead of Peanuts Worldwide LLC, who went to all the streaming companies to sell the rights to.