By "unimportant" I was referring to those things of little consequence, like the size of his t-shirt, the style of his beard, or the twitch of his arm. Often it seems that those who can't effectively argue with the information that's presented will default to picking on such things instead.
If someone isn't fond of a particular teaching style that is certainly fine, as it does indeed matter.
There actually is some argument for picking an instructor that is not shy about language or rough mannerism. We're talking about life saving, not tiddly winks.