How a Christian chooses to protect himself, his family, or his possessions is, of course, largely a personal matter
They seem to be suggesting a sort of "don't ask, don't tell" policy regarding what measures a JW might employ, short of firearms.
I know an elder whose "open secret" was that he kept a baseball bat under his bat for any unwelcome visitors.
As I understand, a bat is considered one of the best defensive weapons in the case of an intruder not carrying a firearm.
spiritually mature Christians choose not to keep a firearm for protection against other humans.
Translation: Keeping a firearm for the purpose of self-defense will get you removed from any "privileges" (elder, pioneer, etc.) but won't get you DF'ed.