I think it defeats a significant part of the purpose if you move it to "Off-topic" because it was effectively the landing page for noobs who wanted to find out about price action with bitcoin (i.e. essentially all bitcoin noobs). This is how the bitcoin noob experience has gone for thousands ...
they go... google search bitcoin CLICK ->
.... hmmm, bitcointalk.com, yep, that looks popular want some of that goodness CLICK ->
... hmmm, Speculation (yep, that's what I'm really here for hehe) CLICK ->
....hmmm, what's this massive long-ass thread with millions of views, yep that's what I want to read WALL OBSERVER!-> CLICK bang, done, arrived \O/
... and down the bitcoin price discussion rabbit-hole they fall

The landing page effect of the rough 'n tumble feel yet warts 'n all authenticity of Wall Observer should not be underestimated.
The best solution would involve it remaining in Speculation, I agree.
And you're quite right in your other posts - the spam will just metastasize somewhere else. Locking the thread ultimately solves nothing.
when OP was active, he is also doing his work and spams were less iirc.
Don't think Adam ever moderated anything in his life. He was also pretty spammy himself at times lol.