In other words, this entire thread is one big waste of time. You've admittedly twisted the story, left out important details, and molded your posts in order to elicit the type of responses you would like to hear.
You paid for your meal before you ate? That seems odd.
The restaurant has security guards? That also seems odd.
You might want to have an attorney in your area personally review the facts of your experience at the restaurant. If the previous robbery was a recent one, it would be reasonable for the restaurant to be on alert and wary, but there was definitely an overreaction, especially if only based on your similarity in appearance to the robber.
I do not know if you have harm enough to support a defamation claim but you deserve at the very least an apology.
You will probably want to write a letter to the restaurant's management and relate your experience. The attorney you see will tell you how best to word the letter.
You are probably smart to discuss your experience at the restaurant with an attorney in your area. Although I imagine there is no legal action you can pursue with success against the restaurant, the attorney you see can determine this better.
The attorney will probably recommend you write to the restaurant's management, explaining what happened to you while you were dining. You should get an apology - and possibly a free meal. The restaurant could have a legitimate defense to their actions that might make a lawsuit difficult at best but I would be surprised if they don't apologize for treating you poorly.