If Thammasat lecturer is innocent, why didn't he stay and prove it?

The brouhaha at Thammasat University over the dismissal of historian Somsak Jeamteerasakul – for failing in his duty as a public servant by not reporting for work for more than 15 days – makes me sick.
If “Ajarn” Somsak thinks he is innocent, why did he run away? Is he good only for spitting venomous words? When he pointed the finger at other Thais for committing treason, some of those fingers were pointing back at him. After all, he’s also Thai, isn’t he?
Vint Chavala