The only way you could disprove him is if he made a prediction, or his work made an implicit prediction, which did not come true.
And this is the precise point that destroys any self-proclaimed prophet everytime.
Only in retrospect do alleged Bible "prophecies" get fulfilled. This is the way WT and similar non-prophet religions work: they look at world events, then make them fit (no matter how tortured the method) this-or-that prophecy, then declare themselves so insightful because they saw it coming the whole time.
The ones who do predict specific dates (Harold Camping, et al) end up with egg on their face, but at least they had the courage to be specific (though foolish). WT tried it with 1914, 1925 and 1975 and failed miserably, although they worked within a year timeframe rather than a day, date and year.
If WT was a true spokeman for god (a prophet) as they claim, they'd put specific dates and events out there and they'd come true everytime.
If I had lived back in Russell's time, I don't know if I would have been frightened by his craziness or impressed by his Bible interpretations, but things are much clearer now.
Mt. 24:36 should settle that issue ahead of time.