Black women on average have higher testosterone than women of other races, and so are more likely to have a relatively “masculine” appearance. That makes such already superficial and nasty memes take on a racial tone.
Ok but this pic was based on her and her physique as Trumps wife was a caricature. Not on stereotypical race features, but on her features. Let’s not read too deeply into it.
Plus, Michelle made a point of working out her arms and making them muscular. She prided herself in showing of her arms. This is something she purposefully did.