A politician that uses a personal tragedy to argue for a policy change is exploiting the tragedy, because to fight against their policy will be seen as attacking them for their tragedy. “How can you question Gore’s commitment to stopping the scourge of smoking, he lost a sister to cancer!!!”
The issue isn't his commitment to the cause, but whether his policy is effective or Constitutional. Gore's obviously committed to cutting down CO2 emissions. So what? The question is whether or not that will benefit the planet its inhabitants.
There will always be people who respond irrationally to emotional arguments. Instead of focusing on winning them back with equally emotional arguments, maybe we should reduce the number of those people by sticking to logic and reason, thus elevating the national debate.