Several years ago the Society published that if an elder commits a serious sin, and keeps it quiet for 2 or 3 years, he doesn't need to be removed as an elder even if the sin is discovered later.
Governing Body members would get at least that much leniency.
Here it is from the Kingdom Ministry. It involves a discussion of what "some years ago" and "distant past" means. The terms can mean as little as 2 or 3 years.
(Kingdom Ministry - October, 1972)
Here it is again, several years later, re-affirmed in the Elder's Manual
(Shepherd The Flock of God, p38. [2010 Elder's Manual])