Actually, we've only just started with dangerous climate change, and simply cutting emissions takes us back down to a safe climate without any disposal effort, so your supposition that there is an existing subsidy is incorrect. For future emissions above the 270 Gt of carbon included in the IPCC's RCP2.6 one might suppose a hidden subsidy, but not until then. We still have a choice not to make too much carbon dioxide waste. That choice is past with nuclear waste, we've already made too much not to have a need to dispose of it. If fact we are backed up and should probably stop producing nuclear waste until we've got the problem solved.