If John Brown hadn't gone bankrupt twice in the wool industry... had he been a factory worker or something that had no direct connection to slavery or slave industry, then his motives could not be misconstrued as something else.
However, whenever you see someone claiming some great moral crusade, like "Climate Change", or "Reproductive Rights", or "Undocumented Migrants", you can rest assured that underneath all of it is a pile of money someone is making or someone is losing.
John Brown spent a lot of time working with Massachusetts wool merchants and other wealthy Massachusetts liberals. It was these wealthy liberal elites who financed his raid.
Certainly a sudden spike in the price of cotton wouldn't have hurt the wool industry any, would it?
I would be loathe to credit “liberals” with the issue of emancipation. Freeing innocent people from bondage is the antithesis of what the left is about.