Al-Iskander
Warlord
As mentioned in the LiveStream, an early Worker is unprotected from Aliens so that choice can lead to an early alien attack wiping out your Worker. It remains to be seen how much warning your Starting Colony might get prior to an attack.
Also, though this is embarrassing, I have more than once built workers in Civ5 before I had researched appropriate improvements. It's frustrating to have to park a worker who can't build / chop what you need him to, while he eats up precious revenue.