Rather easily actually, there are many areas in patrol that have not been opened up yet that could be done as an area for these boss types,. Secondly they are not going to just randomly show up, they have to be activated via some interactive object. Thirdly, These would only be available on the higher level slated patrols as mentioned in the post, reducing the risk to low level guardians gaining access to something that would decimate them, and eventually frustrate them beyond repair. Hope this assuages some of your concerns with the idea.