NikL: Maybe the school is different?
Yes, by the very nature of it being a 'school'
Whereas you would need to be 'exemplary' to be used on the 'service meeting' for demonstrations, or to auxiliary pioneer etc
The requirement for the TMS was not as high - though most publishers/elders didn't really realise
Benefit from Schhol Book, page 282
Guidelines for School Overseers
Enrolling Students. Encourage all publishers to enroll in the school. Others who are actively associating with the congregation may enroll if they agree with the teachings of the Bible and their life is in harmony with Christian principles. When someone expresses a desire to enroll, warmly commend him. If the person is not yet a publisher, you as the school overseer should discuss with him the requirements for enrollment in the school, preferably doing so in the presence of the one who is conducting a Bible study with him (or in the presence of a believing parent). These requirements are the same as for a person to become an unbaptized publisher. They are found on pages 97 to 99 of Organized to Accomplish Our Ministry. Keep an up-to-date list of all who are enrolled in the school.
The exception to this would be 'school' parts when presented as part of an Assembly such as at a Circuit Assembly - in this case the 'student's would then need to be exemplary - ie their BoE would be happy for them to auxiliary pioneer.
I do think though that that recent WT article has created a 'bit-of-an-issue' - I don't believe the actual policy has changed though, it's just that the GB has reiterated the old policy in a 'current' WT magazine, so have brought it to the attention of publishers....