That is an absolute non-issue if he was saying it to his teammates in pre-game or the huddle. Of COURSE he is going to pump his team up and get everyone rallied around the idea that they are the champions and we are just standing in their way. 100% guaranteed that we have had guys like KG or PP say the very same thing in games this year. I have said this to teammates before a game. This doesn't mean that they truly believe they can never be beat, rather they are instilling this mentality into them before the game. Remember that Dick Fosbury quote:
" When you reach that elite level, 90 percent is mental and 10 percent is physical. You are competing against yourself. Not against the other athlete. "
The more they can convince themselves that they can't be beat, the better they will play.
There are SO many more reasons to hate Kobe other than something that is common place.