(emphasis is mine)
“Jehovah’s Witnesses do not involve themselves in political issues or governmental affairs. They have no interest in attempting to influence governmental authorities. (John 15: 18; 17:14, 16) As a result of their spiritual values, Jehovah’s Witnesses do not involve themselves in lobbying, civil disobedience, or movements to seize power or bring about changes in governments or laws.”
“Jehovah’s Witnesses remain politically neutral for religious reasons, based on what the Bible teaches. We do not lobby, vote for political parties or candidates, run for government office, or participate in any action to change governments.”
Notice that they say JW’s “have no interest in attempting to influence governmental authorities”.
Wasn’t the Governing Body endorsing a letter writing campaign “an attempt to influence governmental authorities”?
That was the very purpose for writing the letters; to attempt to influence the government of Russia not go through with the ban on JW’s.
They also said JW’s “do not involve themselves in...bringing about changes in governments”, and “We do not participate in any action to change governments”.
Wasn’t the letter writing campaign an action to try to change the government? That’s getting involved in “governmental affairs”.
So, according to their own literature, Jehovah’s Witnesses violate neutrality.