His thoughts on the current invasion are the same as everyone else's, I'd imagine. It's scary. Skeletons are swarming through walls. But he also knows that he can do something about it; he has men at his back, magical armor, and a sword. The rest of the populace isn't nearly so lucky. He doesn't like the king, but that's not important. The king is asking him to defend the kingdom against an invasion of the undead. That's not a mission you refuse out of spite.

The King ordered all Knights of the Ram to the capital. He's out on patrol, keeping the king's roads clear of bandits. He'll ride at his best speed to meet the king's demand, and likely order the slower common infantry of his host to follow after in their own time. He'll reach the capital with his knights alone. 

As for the coup... He's been around the block. He knows the nobility is rotten, and more than half the Knights of the Ram are too. But he also knows that Kane's decision was one of monumental idiocy. Knights aren't statesmen. They don't know how to run a kingdom. Their duty is to protect the people, not rule them. The system sucks, but it works. He'd rather wait for the current king to die and let another house take over than have the Knights of the Ram permanently destroy their credibility by killing their way out of a crappy leader.

But he also knows Kane. Not well, of course, but they were both Commander Knights - a rank only held by fifty or sixty people in the order. He knows the dude's brilliant, and young, and idealistic. Even if that idealism died in Royce long ago, he can still understand it. He won't hate Kane, but he's also not in a hurry to argue for reinstatement of his knighthood. 

Also - are we in agreement that Kane and Royce are different people? :P