Because Genocide makes a great punchline
Trump tweet- just a few weeks after joking about Wounded Knee:
Today Elizabeth Warren, sometimes referred to by me as Pocahontas, joined the race for President. Will she run as our first Native American presidential candidate, or has she decided that after 32 years, this is not playing so well anymore? See you on the campaign TRAIL, Liz!
The ALL-CAPS portion was exactly how he wrote it...