I wouldn't actually call it being disrespectful, he just applies his own knowledge to Bitcoin and I can very well imagine why he says those things.
It is disrespectful when you call Bitcoin rat poison and laugh when your fellow Berkshire Hathaway board member Charley Munger refers to people here as traders of harvested baby brains. It's disgusting too.
So tell me, how do you interpret the above statements? Can you understand that too?
People also keep asking him about Bitcoin, just because he's one of the most successful investors out there.
But it's commonly known that WB sticks to investments that he understands, so why would he say anything positive about Bitcoin?
Why would he say anything negative about Bitcoin? If someone asks me about something I'm not interested in, I'll just tell that person that I have no clue and don't really care either, and leave it at that.
I have seen other high level investors do exactly that and this is how it should be. It's easier and less of a hassle to follow that route because it would discourage the media from asking the same stupid question over and over.