Although I disagree with most of it - I, too, would be very happy if Warren were Clinton's VP choice - I don't fault Trump's right to say most of it. He's entitled to say Warren has not been productive as a US Senator (though I think she's done a great job), and even that she has a "nasty mouth" (which does have an anti-woman tinge to it, but no one could deny that Warren was nasty about Trump last night - justifiably nasty, to be sure - but nasty no doubt).
But there's one word in that tweet that Trump is not entitled to say, and for which he should be called out by all decent and fair-minded Republicans. "Pocahontas," as used here by Trump, is plain and simply a racial, racist epithet, no different from the slurs that have long been hurled against other minorities.
There is a difference between even the harshest political denunciations, correct or not, and the kinds of demeaning racist comments that roll out of Trump on almost a daily basis. I hope everyone who has even remotely toyed with voting for him, for any reason, in November, keeps this in mind, and what it is doing to our public discourse.