Athanasius:
Despite the evidence, and there is much more, Watchtower apologists will
no doubt argue that perhaps there were two Joseph Franklin Rutherfords
living in Boonville and the one who belonged to the Knights of Pythias
was not their guy.
Your source might be suitable (a screenshot would be nice given the rapid desire for the claim to be true) for passing mention that Rutherford was a member. If the citation is genuine, it's quite strange indeed that it would not have been provided first instead of more ambiguous references. It does not meet the standards for citing it in Wikipedia - need a source that unambiguously identifies him (specifically) to be a member, not a passing mention of a name. Ideally, this would be source discussing Joseph Rutherford.
It's still not clear why Watchtower apologists should want it to be false, or why some here so badly want it to be true, since it would indicate nothing about any later allegiance to the group. JW literature is full of 'life stories' of people who used to be members of some other group.