Richards was violently decked by Tim Jackman as they both entered the attacking zone. Jackman clearly had to try to stay onsides on the play and collided with Richards' shoulder. Richards crumpled to the ice but skated off to the locker room under his own power a few moments later.
Was it a dirty play? I'll let you be the judge. On one hand, Jackman had to stay onsides. On the other, you could make the argument that Jackman looked like he deliberately targeted Richards. I'll leave that up to Brendan Shanahan.
As for Richards' status, he returned to the Kings' bench in the third period. So perhaps the point is moot.