Yes, it is, especially if you're not doing anything to make them not the loudest voices. If you don't like being associated with them, then you need to tell them off, and call them out when they say terrible things like that.
I'm not sure why that isn't an argument to be considered. The fact is these statements (referring to Mexicans as rapists and murders, "shithole countries") keep being made by the president, who historically has some sway over the legislative debate, especially when their party controls both chambers of congress.
I'd like to know, do you think these are reasonable, good-faith openers for debate? I don't, especially when so few on the right seem to be able to rebuke them and move on to a real discussion.
He's saying the definition of the word being used is currently changing.
When racist people start talking about illegal immigrants and they refer to all people of a specific race or nationality, they effectively change the definition of the word.