Slaves, yes. Mindless, no.
It should suffice that you read the two lines right before to understand that it's the WK's personal reflection.
But the Lord of Morgul, seeing no better counsel, determined still to seek northward, hoping maybe to come upon Gollum as well as to discover the Shire. That this would prove to be not far from the hated land of Lórien seemed to him not unlikely, if it was not indeed within the fences of Galadriel. But the power of the White Ring he would not defy, nor enter yet into Lórien.