Sounds like a legitimate reason for withdrawal if you ask me. No penalty necessary.
the rulebook in its words
asks a lot from players to check their injury : either go on-site to have the injury checked or have the injury checked in the tournament where they played previous week, or be out of the Tour for at least one month and provide a medical certificate.
It's not only about being "injured" or not.
BUT the application of these seemingly harsh requirements is in reality very nice to players indeed (the even worst case is the suspension from a Masters 1000 tournament which is still in the rulebook and has never been applied whereas it should have been applied many times by the words of the rulebook)