Correction: "systemctl stop bluetooth" appears to have more durable results wrt suspend/wake than I first thought, though I thought I tested it pretty thoroughly. If I stop the service..., it appears to stay stopped following suspend/wake. For the moment then, my workaround is to set AutoEnable=false and whenever I want to turn BT off..., do a "systemctl stop bluetooth".
Correction: "systemctl stop bluetooth" appears to have more durable results wrt suspend/wake than I first thought, though I thought I tested it pretty thoroughly. If I stop the service..., it appears to stay stopped following suspend/wake. For the moment then, my workaround is to set AutoEnable=false and whenever I want to turn BT off..., do a "systemctl stop bluetooth".