Now, when I saw that pic, I associated the chimp with the royal family. I most likely did tha because my brain likes to see those jokers being mocked.
If I were racist, and race was at the front of my brain all the time, i would have remembered that MM was part black, and then the chimp would have been mocking that.
In summary, racist or not, the people who noticed the race element in that tweet are far more invested in the topic of racism than the average person.