I recently read this article, and excuse me for not understanding Satoshi's explanation, but why is the MIT licensed chosen, when that very license allows closed-source bitcoin-related software to be created, when this very action is against the pro-transparency philosophy?

Unless I haven't acknowledged how licenses work, and if it'd be legally okay to re-create closed-source wallet software from scratch (such as Exodus) even if Bitcoin Core was released under AGPL (which prohibits re-distribution if source code isn't going to be disclosed).