To answer my own questions: his parents were/are JWs. He grew up in San Diego (next to Beth Sarum) and was a "collector of Watchtower memorabilia" back in the 1980s. His mother was a JW in Canada and experienced persecution. So he may consider that he has a personal angle on persecution.
Watchman (who I think is Robert King?) says he met him in the 1980s.
http://documents.adventistarchives.org/Statistics/ASR/ASR2016.pdf
He is apparently not married. Or else it's not mentioned on either JW website or JW survey.
https://www.jw.org/en/publications/magazines/w20130715/new-member-governing-body/
http://jwsurvey.org/cedars-blog/mark-sanderson-confirmed-as-new-governing-body-member
He may have been one of the key people behind the 2013 NWT revision and the new Bible collection exhibit at Warwick.