That would be stupid, Apple doesn't make money from users data, Apple doesn't listen to conversations like Google does to sell ads.
So why would they support servers (and there are a lot more of android users than iOS users) for people that didn't bought anything from them? For people that bought Androids to like them? They don't need that.
It has nothing to do with open source, the open source community doesn't need this and Apple couldn't care less about the GNU types after GPLv3 incompatibilizes with their business (while Android OEMs break the license every single day, but the community turns a blind eye, because it's Google)
Also, they would lose a few of their product sales and lots of 30% shares on sticker packs and other Apps for iMessage they sell.