What do you mean by "call"?? You mean, like, "assign" a certain pastor to a church?? Or are you saying that they should be married first, before they're given (elevated) to a high post (such as "Bishop")??
And ... while I can understand the 'rationale' (as you've explained it) behind that kind of decision-making process ... it's still rather ... disturbing ... to me that such politics would come into play when it relates to a spiritual leader.
I mean ... I just think a man (or woman's) spiritual qualities should be the first indicator by which to choose him (or her) to be a spiritual guider. Whether or not they're married (or the suspicion of somebody 'going after' somebody else within the church) is already an indictment of the sanctity (or lack thereof) of what the church is supposed to be about!!
I mean ... if you can't start with the trust/faith that everybody is gonna do the right thing .... (clergy and congregation alike!) ... by not doing the wrong thing, at the very least ... they it seems to me you're already starting the process 'behind the 8 ball'!!
Again ... if you can't trust the clergy (and it sounds like even the church doesn't do so, itself?) ... who are you supposed to trust??