Here's why:
*** w88 11/15 pp. 18-19 pars. 17-19 Helping Others to Worship God ***
17 The elders are responsible to ‘shepherd the flock of God in their
care.’ (1 Peter 5:2) If two elders offering help determine that an
unbaptized wrongdoer is unrepentant and unqualified to be a publisher,
they will inform the individual. Or if some unbaptized one tells the
elders that he no longer wishes to be recognized as a publisher, they
will accept his decision. In either case, it is appropriate for the
Congregation Service Committee to have a simple announcement made at
an appropriate time, saying “ . . . is no longer a publisher of the
good news.”
18 How will Witnesses thereafter view the person? Well, at an earlier
point he was an ‘unbeliever’ attending meetings. Then he both wanted
to be and qualified to be a publisher of the good news. This is no
longer the case, so he again is a person of the world. The Bible does
not require that Witnesses avoid speaking with him, for he is not
disfellowshipped. Still, Christians will exercise caution with regard
to such a person of the world who is not worshiping Jehovah, even as
Israelites did regarding uncircumcised alien settlers. This caution
helps to protect the congregation from any “little leaven,” or
corrupting element. (1 Corinthians 5:6) If at some later time he
expresses a genuine desire for a Bible study to be held with him, and
this seems in order to the elders, perhaps it will help him come to
appreciate again what a privilege it is to worship Jehovah with His
people.—Psalm 100.
19 If the elders see that a certain person of this sort is an unusual
threat to the flock, they can privately warn those endangered. For
example, the former publisher may be a youth who has given in to
drunkenness or immorality. Despite the announcement that he is no
longer an unbaptized publisher, he might attempt to socialize with
youths in the congregation. In that situation, the elders would speak
privately to the parents of the endangered ones, and maybe to those
youths also. (Hebrews 12:15, 16; Acts 20:28-30) In the rare case of a
person who is disruptive or violently dangerous, he can be told that
he is not welcome at the meetings and that any attempt to enter will
be considered trespassing.