To clarify:
These weren't Milan players. It was a bunch of actors that were paid to do this haka dance as part of a marketing campaign Milan is involved in.
As much as I love watching the All-Blacks carrying out their ritual dance before a game, it's ridiculous to see Milan do something like this. It's random, comes out of the blue, and it looks like the club is more busy trying to please their sponsors than stop the team from having a shit season.