Just to contribute, I fly the 737NG aswell and indeed there is no protection.
We're using the same policy as a crosscheck for having recieved T/O clearance to arm the A/T only after it.
It flows nicely and there is no confusion about what level of engagement the automatics are in.
It would be quite a rumble if I'm behind an A/C that by accident starts putting on TO/GA power.
Remember that spool up on a 737 is not that long anyway, by far not as long as some of the bigger engines that are out there.
So i find the procedure for fleet communality bollocks because it's not safe!
SZ