Here's the Court Order (PDF).
So as I understand it, Sprint has to maintain WiMAX at the same service level for the duration of the injunction. It had to cease shutting down additional areas.
WiMAX runs on Single Mode Legacy Gear (which it has to keep in place to keep WiMAX on. This gear has to be swapped out to upgrade to LTE.) WiMAX also runs on newer dual-mode Clear Gear, which can be switched over to LTE and not require an immediate swap-out.
The Karma Hotspot is an LTE device.
The issue was the non-profits were receiving Unlimited Data for their hotspots over WiMAX and wanted that level of service to continue over LTE after the switchover. Apparently, Sprint wasn't offering the same deal. So, I'm saying, just send them Karma LTE hotspots which have an Unlimited Data Plan and use Sprint's LTE network. Of course, they're capped at 5Mbps...
It's also worth noting: