Comment on "Dynamic Opinion Model and Invasion Percolation"
  In J. Shao et al., PRL 103, 108701 (2009) the authors claim that a model with majority rule coarsening exhibits in d=2 a percolation transition in the universality class of invasion percolation with trapping. In the present comment we give compelling evidence, including high statistics simulations on much larger lattices, that this is not correct. and that the model is trivially in the ordinary percolation universality class. 
A. Sattari, M. Paczuski, and P. Grassberger
physics.data-an cond-mat.dis-nn