you're only accounting for the cost of what it takes to craft a wood frame, I'm talking about having to use wooden blocks instead. That would make the resources (and time) spent go up by a bit (frame = 2 wood -> upgrade with 4 wood. TOtal of 6 wood spent per block and it can even be balanced out to cost like 10 wood per wooden block). 10 wood may not be much, late in the game, but its a fair amount of resources early (if you consider how much time it takes to cut a tree with a stone or iron axe and the repair involved). So if people are still doing nerdpoling with wooden blocks, at least now they are using much more resources and time to do so. Yes, you could recoup some resources by breaking them (as of now, I believe you get 2 wood back per upgraded block), but getting down from a wooden pole you made by breaking the blocks on the way down doesnt give you back all the resources used and also consumes a lot more time than just picking them back up - as it is now. (and thats not accounting for the repairs on the tool used to break them)The loss in resources would be negligible (2 wood for a wood frame). And no need to find another way down, after using the blocks to get up, you could just break them to get down and you'll even recoup some of the resources.
So while it may not entirely fix the problem, it will balance it out a lot and postpone abuse.
The other option would be to only allow construction blocks to be placed in LCB'ed areas. Which would require the LCB cost to be changed.. 5 stones for crafting one and become able to nerd pole to the shotgun messiah rooftop is still a piece of cake)