So quitting politics, in fact retiring, in fact bailing on Greece, to write books and give interviews to Sky is enough to make him an hero to Europe's working class?
He resigned the night of the referendum, when he understood that the government is going to capitulate. Maybe in some countries that's nothing special - as it should be. When you're not on the same page with what the government does, you retire and let someone else who believes in the solution, implement it and then pay the piper.
In Greece, I know of NO politician in 50 years, who retired promptly when his views and gov's views stopped being aligned.
So regarding Greece, that's a huge deal and gives him alone more credibility that the last 10 Greek governments put together.