It's much more likely that Zuckerberg realizes his company is overvalued, and that he needs to acquire a massive amount of users to make up for that gap.
Subsidizing a walled-garden version of the Internet where users can only use Facebook in developing countries makes strategic sense for the company.
Facebook doesn't care about "free internet", they care about building their business, and this "free basics" program makes that patently obvious. I don't blame them or necessarily think it's a bad thing , but the propaganda associated with it is ridiculous.