There's a whole section on the memory implications: "Another change, which created a bit of controversy over the life of the patch, disables hibernation when a secret memory area is active."
Based on that, I doubt they ignored the problem of swap space. My guess is that the region of memory is designated unswappable, as was already possible before.
Ideally there would be a way for the OS to signal that it's going to hibernate, so that the application can get rid of the secret stuff (overwrite with zeroes etc) and go to a state that, when back from hibernation, would ask for a password again.
Or even, disable this when hibernating to a swap inside an encrypted luks partition (which also asks for a password when it wakes up)
Based on that, I doubt they ignored the problem of swap space. My guess is that the region of memory is designated unswappable, as was already possible before.