Steve, the essential point of your argument here is correct. More productive investment is needed in research and innovation to develop clean energy options that are cheaper than coal. See my book, Energy Innovation, for a plan to do that.
You also are right that divestment makes little sense, potentially inflicting financial harm on those who divest while accomplishing nothing more than a feel-good gesture. Any impact on stock prices of divestment will be trivial compared to the effects of the kind of market forces that have lately made oil so cheap.
However, while it is better to "accentuate the positive and eliminate the negative," I think you may overstate the case for psychological tactics aimed at cultural transformation. In a world where population and demand for energy are both growing, especially among developing nations, there is little reason to believe such ploys will make much difference. What will have a big impact, again, is the development of alternatives to fossil fuels that can provide reliable energy at a cost that is at least equally affordable.