The Concentration camp Jehovah's Witnesses weren't actually "Jehovah's Witnesses"--they were Bible Students.
Interestingly, the more you parse this--the more clear it becomes: the reason Rutherford changed the name from International Bibles students is that
they were AT ODDS with what HE was doing and saying and printing! These bibleforschers were more Pastor Russellites than Rutherfordites.
So, when the Watchtower Society makes the Concentration Camp victims billboards for "True Religion" they are really condemning themselves!
EVERYTHING both the Bible Students and later Jehovah's Witnesses believed about the "signs of the times" has been proved by history to be FALSE
It comes down to this.
Jehovah's Witnesses aren't true "witnesses" unless they take their publications to others.
The publications make false predictions about the world ending.
So, what they are "witnessing to" is a lie.
They are very proud of being door to door liars.
Hardly "bragging rights".