While playing last night, I called for support and eventually the request got aborted, not because I cancelled it but I assume because the support ship died, though I'm not entirely sure. After that though, I couldn't call for support the normal way (C-5) and the comms menu only had the option to abort. I can't remember exactly, but I think it still showed up in the all ships comms menu (C-1) but it didn't respond to any orders, probably because it was dead. Once the other player called in another support ship, I could rearm by giving an order through C-1.