Sorry for the late reply, I didn't notice that I got a response. It is likely too late for this, but I'd like to share my thoughts on licensing, both for my own submission and on potential GPL submissions.
Since you asked how I might license my submission, I lean towards MPL because I consider it a decent balance between copyleft's tenet of "I give you the source code, you give me your changes back" while still being flexible in how it allows code reuse. For a large scale, open source project I would likely lean towards GPL, but for a jam submission, let alone one whose purpose is education, something less restrictive is more appropriate.
That being said, I would only choose MPL if I can realistically expect there even being outside changes to merge into upstream. This is a jam after all, and I may end up producing something so small that any copyleft at all would just get in the way. Although I'm partial to Apache or WTFPL, should I choose a fully permissive license, I would likely go with MIT as per your reasoning.
I also personally disagree with banning GPL (restrictions and all, it's still open source), but you're right in that it should be discouraged for this jam, and I doubt there will actually be any GPL submissions anyway. And at the end of the day, these are just the opinions of one guy; every license has its time and place, and permissiveness was an excellent choice for something in desperate need of software freedom as a game engine.
Sorry for being long winded and opinionated. Thank you very much for responding and taking my suggestions into consideration. Hope all goes well, and regardless of whether or not I participate, I look forward to seeing the entries!