I'm not wishing harm on Hillary Clinton, and to be honest I don't really believe that there's anything wrong with her health anyways. But as someone who disagrees with her politics, and does not wish to see her become president, I absolutely hope this hurts her campaign and helps Trump to furthur chip away at her lead as he has done in the past 3 weeks (back within 4 points on RCP!)
I compared it to the Tank Photo because it also happened in early September while Dukakis had a sizeable lead in the polls. Although I suppose the key difference is that the Tank ride was a completely unforced error while Clinton's coughing fit was simply bad luck.