As per the fine print for that promotion reads:
Get a new phone and we’ll pay off your current phone and service contracts – up to $650 per line or $350 in early termination fees, via prepaid card.
New financed or leased device, qualifying credit, port-in from eligible carriers, and qualifying service required.
I don't see why not. However, you must:
Submit proof of balance & 60+ days in good standing w/ carrier within 30 days of port-in and be active and in good standing when processed.
That means that you need to be at least 60 days in good standing with the carrier. I am not too sure if both carriers take military suspensions as "good-standing."
For the best possible help and most up-to-date information, I recommend that you call T-Mobile at 1 (877) 453-1304, or 611 from your T-Mobile cell phone. Keep in mind, this forum is not answered wholly by T-Mobile representatives. Some, like myself, are just here to lend our expertise, but we are in no way connected to T-Mobile as employees.