I'm not familiar with the order of positions of responsibility within the Jehovah's Witness society.
I do know for sure that Bob was a prominant member in many ways ,which may explain the press's usage of the word 'senior'.
He is a member of a large extended family of Witnesses who, it seems, had managed to 'recruit' a substantial number of potential bible students. However, I know of one family who were eager to become Jehovah's Witnesses because they mistakenly trusted Mr Robert Bill and believed all of the watchtower publications and thier interpretation of the scriptures, but were rejected because they were unemployed and thier child (a boy) had Downs Syndrome (I was told this by a former 'Jehovah's witness') and therefore would not make good winesses.