JOEL - President Gordon B. Hinckley said:
"The requirements of a bishop today are as they were
in the days of Paul, who wrote to Timothy:
“A bishop then must be blameless, the husband of one
wife, vigilant, sober, of good behaviour, given to
hospitality, apt to teach;" (1 Tim. 3: 2-5)
(Gordon B. Hinckley, “The Shepherds of Israel,”
Ensign, Nov. 2003, 60)
Brigham Young said of this scripture:
"(Paul's) advice to Timothy amounts simply to this—It
would not be wise for you to ordain a man to the
office of a Bishop unless he has a wife; you must not
ordain a single or unmarried man to that calling."
(Journal of Discourses, vol. 2, p.88)
There is logic in requiring a Bishop to be married,
because if he were not, how could he give proper
counsel and instruction to those over which he
presides without himself having experience in managing
a family? This view, moreover, is supported by the
context, wherein Paul remarks that a bishop must be
"one that ruleth well his own house, having his children in
subjection with all gravity; for, if a man know not
how to rule well his own house, how shall he take care
of the church of God?" (v. 4, 5.)
I can see how these scriptures might preclude a single
or single divorced man from being a Bishop, depending
on the circumstances.
I do know that a widowed man who was sealed to his
wife can be a Bishop, because he is still married to
her. But if a man is divorced he of course is no
longer "the husband of one wife", and therefore is not
normally called to be a Bishop. If a man divorces his
wife while he is Bishop he is usually released
from his position(this could happen for other
positions as well, eg. Stake Pres, Relief Society
Pres., Seminary teacher, etc.). There is some wisdom
in this since a person suffering through a divorce is
not likely to be able to function very well in any
position.
These things are looked at on a case by case basis but
I do know that a previously divorced man who is
currently married to someone else can become a Bishop.
Most important is that they are currently married at
the time they are called to serve as Bishop. So your
friend is correct, but only if he is currently single.