Favoring Language Change - Idioms

This topic seems to be more controversial than a simple dictionary definition would lead one to believe.

At issue: If a man is favoring his right leg because of an injury, which leg was injured, his right leg or his left?

Idiomatically speaking, dictionaries seem to favor the interpretation that the the right leg is the injured one.

Here are the pertinent entries from merriam-webster.com and dictionary.com respectively:

favor verb

1. a : to regard or treat with favor
b (1) : to do a kindness for : oblige (2) : endow
c : to treat gently or carefully <favored her injured leg>

and

14. to deal with, treat, or use gently: to favor a lame leg.

However, consider these responses from a similar question posed on Yahoo:

"When you favor a leg, you give it more work. example: if you injured your left leg, you would favor your right leg so you didn't have to use your left as much." - Lackadaisical.One

"Essentially the same thing here. If you favour your right leg, that means it is your favourite leg to use, i.e. you prefer using it to your left leg. That means you put MORE weight on it." - Amanda

And my favorite:

"my advice would be to ask a question that makes sense next time" - bluffenw/maimuffin

The analogy I have always used when told that I have it all wrong is this -

A teacher's pet is a favorite; therefore, the teacher favors that student by calling on said student more frequently than other students.

For this reason, I call on my right leg more frequently when my left leg is injured.

Either way you look at it, I believe that the examples of language in use coupled with the way language is constantly changing allow for both versions to be favorable.