9/10 time sif you let a suspect RP surrender they turn and kill you a few minutes later. I would be more open to the idea if I could trust people more but experience has taught me otherwise.
It's always a matter of trust, if you expect change you have to do something for it. Althought this has never happened to me, or happened a few times out of all the arrests i've done ever since we stopped enforcing /gu long ago (I know it was never supposed to be enforced)
As for the question itself, no it's not allowed, If cops keep doing it then we will remove /engine once and for all. Gandalf himself said the conditions for the command to return were for cops not to force it's use. In my personal opinion, i don't know why administrators haven't seen that and think otherwise.