Yes, someone in Trump's administration joked that McCain can be ignored because... he's dying. A few points.
I make more crass jokes than this on a regular basis. Consequently, watch me not cast stones about this specific joke. One thing I am not is a hypocrite. Another thing I am not, though, is a government employee. My job is to study government, write books about it, and teach about it. I have a sideline hobby as a heckler of government, hence this pretentious, little blog.
Making crass jokes about McCain's impending death? Yup. I'd do that/have done that. Trump does worse ten times before breakfast every day. But, you see, that's a problem.
What is interesting is that Trump can call Ted Cruz's wife ugly and accuse his father of assassinating Kennedy, and still Teddy will come groveling back to Donny-boy's feet. McCain really doesn't have that much more self-respect. He voted against the healthcare bill, along with Collins and Murkowski, but the closest he has come to real criticism of Trump since the election has been disinviting Trump from his funeral, which leads me back to easy jokes about McCain dying. Come on, Corker and Flake have mustered more courage than that, and all they're doing is retiring. McCain cast one vote against "skinny repeal," but then voted for a tax bill that included a repeal of the individual mandate anyway, thereby undoing his supposed act of courage on healthcare reform, so really, has McCain stood up to Trump at all?
No. No, he hasn't. And remember, his healthcare vote was supposedly about process, and the tax bill he supported followed an even crazier process, with the bill being written literally by hand, on the margins of the page, at the last minute. I'm not a hypocrite, but John McCain is. Once he dies, though, don't worry. Lindsey Graham will carry on his legacy.
My point here is that Donald himself can get away with saying anything he wants about McCain and McCain will still cave.
Whether or not others can get away with that kind of thing is another matter. At a lower level? You probably don't want your underlings making jokes like that. This is the special privilege of the world's greatest shitbag. Trump could murder a fellow Republican's children, feed them to him, and that Republican would thank him for the meal.
One of his staff, though, should be more careful. Or, leave government. The rest of us can bask in the glory of the first amendment.