Isn't it weird, that an image of a sad cartoon frog is considered a "hate symbol", the same designation as a Nazi swastika? 

On that same note, why would an "OK" sign be designated as a hate symbol?
Hell, for the sake of discussion, why is the swastika a hate symbol at all?
Isn't it the case that the swastika was originally a Hinduism and Buddhism symbol for divinity and spirituality (and still is)?
Then why oh why would it induce hatred in some people and solidarity in others?
In my opinion, in cases like these, the prosecution of a hate symbol is precisely its source of power.
Because people react negatively, and sometimes even violently, toward some symbols, these symbols became powerful in inciting hatred.
Because people prosecute those symbols, like-minded people who relate to the symbols can rally behind them and find meaning in defending these symbols.
So, in a great irony, the very people who are offended by the hate symbols are the people giving them their power.
In a sense, it is very tautological: The hate symbol is a hate symbol because some people hate that symbol.
In practicality, however, this is problematic. This means that the very hatred generated by these hate symbols will feed more power to these symbols, which, in turn, generate even more hatred, ad infinitum. A positive feedback loop that is very negative for those who wish to extinguish these hate symbols. 
Therefore, the best course of action one should take (if one wishes to extinguish the symbols of hate) is to appropriate these symbols. Normalize them, mundanize them, flood them with inane imagery and ideas to the point they lose all meanings whatsoever.
Remember: Don't feed the trolls. That will only make them stronger.
And start using that OK sign to, you know, say OK.
And start using sad frog meme to say that you are sad.