No idea about the Tweets, but he often plays (played) a segment on his show 'Monkey's dressed as famous people played to fairground music' which is where the connection to the chimp picture comes from.
Not sure I follow your line of thinking connecting a picture of a chimp with racist chanting at football matches but totally get your point about public figures needing to remain uncontroversial, it is why we get homogenised soundbites from footballers in post match interviews. Dull.
You've taken the incident out of context. He has an ongoing gag with monkeys dressed as famous people, Katie Hopkins does not.
As The Clamps says, the outrage is from people coming to DB for the first time. Unfortunately for Danny he didn't pick up on the racial overtones that would be implied...