Legendary Hot Time Event 3 - Saturday, 1/14 @ 2:30 PM

Seems likely, yes. I think they just don't want you in a map where you'll die if Cassandra pops up on you.

You can get the boxes just fine in normal training maps, though.
It's the special maps - generally speaking, the ones you can't tele into - that supposedly don't work. (Although I think someone said, at an earlier hot time, that they got it in FM?)