It wasn't that Walker thought that Alera and Su would end up injured, it was the fact that the speedy strikes used against Su were pushing her to use more of her strength than normal. Meaning that she would most likely start ramping up the output of her attacks.
However, it was clear that the popularity and rumors of Su's offensive shield style had been brought to the demi-human lands. Alera was dodging any attempt to be slapped or deflected by the twin shields. Yet, she was still not landing a single blow at all.
"Your arrogance and disrespect to our king is clear. You should not wish to stand on the same level as someone who supports our entire nature." Alera was doing what many nobles or royal guards would do if they felt that their king or lord had been dishonored. It was an older way of thinking but not one without merit. She possessed loyalty to Rorick and the demi-human people beyond a doubt.
