by yellow wire, do you mean of these three wires, power, gnd, and "ign/acc" or whatever? Like what the opus takes?
and by "remote output" do you mean the signal that tells the amp to turn on or off?
If the answer to both of those questions is yes, then the answer to your question is yes, it's safe. The remote signal on the amp uses VERY little current. Low enough that it's safe to ignore it for this purpose.