If you research the topic of force and it's initiation you'll find fraud comes under that. Objectivism holds that any moral trade/transaction is between willing partners with all relevant facts (such as can be known) known to all.
It seems to me that keeping wages paid that you did no labor for could be construed as a type of fraud. (If I'm incorrect in technical legal aspects, forgive me. I'm no lawyer. I am sure you will catch my drift)
Looked at another way, if you were the employer, how would you look at it?