Sounds like a legitimate reason for withdrawal if you ask me. No penalty necessary.
Of course I make no accusations/judgements here regarding the withdrawal per se. That's up to the tournament and tribunal. I only point out the expectations especially given his history with the tournament. Regardless of injury, It seems like he could have been involved in the promotional activities and people would have been happier.
But this strays from the thread topic.
and needs no discussion here.
On topic, I still wonder why no 0 pointer for Basel, based on the rulebook.