As per usual with this kind of issue there's far too much midslinging and too little effort to think ahead by most parties involved.
For starters, it's totally easy to see why he did it. You can see the reason for Bernardo making the comparison and once upon a time (which I imagine many on here are from) it was perfectly acceptable behaviour. More importantly, it's still considered acceptable in some places, like Portugal. On top of that, he's living the sheltered life of a footballer, and if his black friends like, everyone else (in public) should too right?
On the other hand, it's easy to see why it's considered inappropriate and wrong. The character is based originally on a stereotype which has it's roots stemming back centuries relating to racial prejudice and persecution. The world's become wiser, people are more in tune with what's ok and what's not. Eddie Murphy's stand up from the 80s was incredibly homophobic but back then it was ok. Now it'd be considered extremely offensive; the fact that it used to be ok doesn't make it ok now. That's how it is here.
Besides, whether people get offended or not isn't the problem. In fact getting offended about it is being naive and truthfully unhelpful. The issue is whether it was wrong to make that tweet, and why. So calling out those offended people, ignoring why the tweet is inappropriate, posting some ironically hypocritical quote about being offended from the same Stephen Fry that closes his twitter account every time someone calls him a name, and referring to some token black guy that thinks it's ok, is also not in anyway helpful.
Things like this should serve as an opportunity to educate. Those who are condemning Bernardo should be educated on context, nuance, background, and understanding the difference between ignorance and hate. They can be taught on why Bernardo may have made the tweet, or more relevantly why he thought it was ok. They can learn that not every "bad" act happens because the person is bad, or at least when that is and isn't the case. And they can learn from it to pick out others who might make the same mistake Bernardo did and help prevent it from happening by teaching them, so that the world becomes closer to the more sensitive one they crave. And more.
And those getting angry about the fact this is an issue can also be educated. They can be taught as to why black caricatures based on racial prejudice are wrong. They can be educated about the history of it, the feelings about it from the black communities and develop empathy as to their historic struggles and why we should be considerate and understand it doesn't relate to the white life. We should learn to translate these lessons for more than racism. It should be taught to understand that many people don't choose to be offended and that emotions are difficult to control; just look at the matchday threads, it's all around us! It should be taught why using the term snowflake is not addressing the problems at hand. And more!
Bernardo did something that was wrong. You can spend 500 pages arguing it was ok for whatever reason but it's not 1995 anymore and it won't be again, so it's not ok. That doesn't mean Bernardo is a racist. In fact every account has him as a great and caring guy and it's difficult to dispute that. He made a mistake. An innocent mistake even. We all make mistakes. He's just unlucky his was in the public eye and on a sensitive issue with an unsympathetic media circling, but that's just how it is.
Should he be punished? No. Not because what he did was ok, but because it was a naive mistake. Any punishment, whether it be a suspension, fine, or just a reprimand would be completely nonconstructive, ESPECIALLY for something that it such an outlier in Bernardo's story. Making an example out of Bernardo would not stop racism. It would just piss a few people off and render everyone else frightened to do anything. Imagine how stupid it would be for Pep to drop Aguero because he missed a penalty. Think of how much that'd annoy the players, upset Aguero, be harmful to the team in general by not playing him and scare everyone from penalty duty. That's what punishing Bernardo does.
Again, this should be used as an opportunity to educate all those involved and all of those around us; you can never beat hate with more hate. Unfortunately, the FA and Kick it Out seem more concerned with looking like they care than actually caring, so a punishment is likely. Let's hope not.