Why Can't A Single Man Be The Senior Pastor?

Is it biblical unfair for churches to state and seek only married men preferably those with children for a senior pastor position?.....Why can't a person be an effective senior pastor if unmarried?....If it's not biblical then why do so many black churches ask that a senior pastor be married?....I know we in the black church house love to quote Paul....But Paul starts the book of 1 Corinthians chapter 7off talking about singleness and marriage....Paul said “It is good for a man not to marry”he goes on to say it's good if  "all men" were single, celibate, and serving Christ without the weight of a spouse and children.

So, when and why did the church whip up this idea that a man must be married in order to be senior pastor? My son-in-law is a young  senior pastor who at one time were passed over for a senior pastor position because he wasn't married.....He said  single people are treated differently when it comes to ministry....And that most black churches will not hire you if you are single....I know someone is going to mention 1Tim. 3:2 but that particular verse is talking about bishop overseers and not pastors....I honestly believe when the time come to interview for a senior pastor position....The church should focused more on finding single/married men who are Holy-Ghost filled and eager to do the will of God.