Thanks for the info. I was able to reproduce it, I believe...
If you deactivate the turrets and wander in and shoot things up, there's a second wave of RSM that come running up from the farm. Depending on how many were left, they could be spread out across the whole distance. It's a little awkward if you skipped the farm and rush out the Prison at the end (spend time collecting loot and such and it should feel better), but you can fight your way down if so. The turrets will be highlighted as enemies during this combat, however, they aren't pulled into combat... unless... unless you shoot them. Upon shooting them I got my arse handed to me, as one should if waking the dragons.
I now have them ignore combat when deactivated, so you should be good now. Well, when it's released.
Pro Tip: the turrets will ignore combat when deactivated, meaning you can shoot them all day long and they won't shoot back. However, the RSM may not think too kindly of Rangers that destroy their property. FYI
Thanks for the info!