Using heat to cook (mock) ceviche
The problem I see with cooking fish to dress as ceviche is achieving the texture.  Citrus juice firms the raw fish while baking, for example, will produce either tender, fall apart fish or dry overcooked fish.  Possibly bay scallops may survive in this substitution but I don't think so.  The reason I make or purchase ceviche is for the fresh, clean taste.  Not fishy.  Another suggestion would be using surimi which is already prepared to have a nice texture.  In the US it is called imitation crab or lobster usually made from pollack.  Just one final comment.  Consider the long history of this dish, and it goes back to before refrigeration.  It's unlikely there is any grave danger from using this process.  Buy a fresh, cold water fish, dice it, add the ingredients that you like, wait the required time and enjoy.  Relax!  Otherwise see www.trans-ocean.com for one surimi source.