That's perfectly legal.
Trump is urging the terminally ill to hang on until the election so that they can vote for him as reported by Newsweek.com.
Trump was speaking at a campaign rally in Nevada. "I don't care how sick you are," he began, and he really meant it--he doesn't care how sick those people were. "I don't care if you just came back from the doctor and he gave you the worst possible prognosis, meaning it's over," he said, defining the word 'prognosis' for those not medically inclined.
He went on: "Doesn't matter. Hang out till November 8th; get out and vote. And then, all we're gonna say is, 'We love you and we will remember you always.' Get out and vote."
You may think that Trump is coldhearted to say such things, but at least he says them because he lacks a brain-mouth filter. You never have to guess what he is thinking, and you never need to go to Dictionary.com to understand what he's saying.
Hillary Clinton, on the other hand, thinks exactly the same way as Trump, but she has a brain-truth filter and it works just fine.
When she wants to say "Hang on till November; get out and vote," her filter helps her words come out as: "I care how much you are suffering and in my heart I am suffering too. Donald Trump doesn't care if you die, but only after the election. I want you all to live long, fruitful lives, and with the Affordable Care Act and the changes I plan to implement, you will. I will extend your lives and the quality of your life, but I cannot do that if I don't win in November when I hope to become your FIRST FEMALE PRESIDENT OF THE UNITED STATES OF AMERICA!"
While Trump adds: "And don't be foolish, folks. Don't buy green bananas, just in case."