I remember, back in the 1950s, going as a "hobo" was as common as going as a witch or a ghost. But in the 2020s, it's so obviously insensitive that one wonders how she could have thought it was a good idea. My theory is that she thought her own real-life image was so strongly the opposite of a homeless man that everyone would
get it. She's incredibly neat and put together and made up and smiling, not smudged with dirt and disheveled. And she would never need help getting food. She's a
provider of food, always helping others cook and arrange food. So — ha ha — she's going as the opposite of Martha Stewart.
Compare
Donald Trump, going as Donald Trump to his Mar-a-Lago Halloween party. He said he only had 10 minutes to get ready. But if he'd had a little more time, maybe he'd have come up with Martha's idea and assembled a costume that would read as the opposite of Donald Trump. What would that be? Undo his usual hairstyle. Wipe the orange off of his face, if it comes off. Get rid of the red tie and boxy suit and go with baggy shorts and an oversized t-shirt with that big Obama logo.

See? That would be funny.
But Martha as the opposite of Martha... not funny.