"...who investigate the activities of the WTS...." jw's are not allowed to truly investigate anything about the org even the early history. They accept the revisionist water downed version put out by the org itself.
If one is told certain things about the history they can simply go to the elder and he will tell you that 'mistakes' were made, human error, etc.... the jw can merrily go on their way satisfied that the wt has done all the homework needed and any mistakes were not that bad anyway. The mistakes didn't really impact peoples lives in a negative way and so on. I know this because that is exactly how it went down in my house when my jw joined up and I tried to tell him about the wt. From the early history, doctrinal, procedures, you name it I tried to tell him. The elders had an answer for everything and could just lump me in with satan trying to sabotage his 'relationship' with jah. ah, you know the story......
jw's by and large are an intellectually lazy lot, in my opinion.